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1.  Creatine Supplementation and Swim Performance: A Brief Review 
Nutritional supplements are popular among athletes participating in a wide variety of sports. Creatine is one of the most commonly used dietary supplements, as it has been shown to be beneficial in improving performance during repeated bouts of high-intensity anaerobic activity. This review examines the specific effects of creatine supplementation on swimming performance, and considers the effects of creatine supplementation on various measures of power development in this population. Research performed on the effect of creatine supplementation on swimming performance indicates that whilst creatine supplementation is ineffective in improving performance during a single sprint swim, dietary creatine supplementation may benefit repeated interval swim set performance. Considering the relationship between sprint swimming performance and measurements of power, the effect of creatine supplementation on power development in swimmers has also been examined. When measured on a swim bench ergometer, power development does show some improvement following a creatine supplementation regime. How this improvement in power output transfers to performance in the pool is uncertain. Although some evidence exists to suggest a gender effect on the performance improvements seen in swimmers following creatine supplementation, the majority of research indicates that male and female swimmers respond equally to supplementation. A major limitation to previous research is the lack of consideration given to the possible stroke dependant effect of creatine supplementation on swimming performance. The majority of the research conducted to date has involved examination of the freestyle swimming stroke only. The potential for performance improvements in the breaststroke and butterfly swimming strokes is discussed, with regards to the biomechanical differences and differences in efficiency between these strokes and freestyle.
Key PointsCreatine supplementation does not improve single sprint swimming performance.Creatine supplementation does improve repeated interval swim set performance.Creatine supplementation does improve power development in swimmers when measured on a swim bench ergometer.As a result of the high energy demands of the butterfly and breaststroke competitive swimming styles, potentially, the benefits associated with creatine supplementation and swimming performance could be greater when swimming butterfly or breaststroke, compared to the commonly examined freestyle swimming stroke.
PMCID: PMC3818661  PMID: 24198677
Phosphocreatine; breaststroke; butterfly; ergometer; power; gender
2.  Does Combined Dry Land Strength and Aerobic Training Inhibit Performance of Young Competitive Swimmers? 
The aim of the current study was twofold: (i) to examine the effects of eight weeks of combined dry land strength and aerobic swimming training for increasing upper and lower body strength, power and swimming performance in young competitive swimmers and, (ii) to assess the effects of a detraining period (strength training cessation) on strength and swimming performance. The participants were divided into two groups: an experimental group (eight boys and four girls) and a control group (six boys and five girls). Apart from normal practice sessions (six training units per week of 1 h and 30 min per day), the experimental group underwent eight weeks (two sessions per week) of strength training. The principal strength exercises were the bench press, the leg extension, and two power exercises such as countermovement jump and medicine ball throwing. Immediately following this strength training program, all the swimmers undertook a 6 week detraining period, maintaining the normal swimming program, without any strength training. Swimming (25 m and 50 m performances, and hydrodynamic drag values), and strength (bench press and leg extension) and power (throwing medicine ball and countermovement jump) performances were tested in three moments: (i) before the experimental period, (ii) after eight weeks of combined strength and swimming training, and (iii) after the six weeks of detraining period. Both experimental and control groups were evaluated. A combined strength and aerobic swimming training allow dry land strength developments in young swimmers. The main data can not clearly state that strength training allowed an enhancement in swimming performance, although a tendency to improve sprint performance due to strength training was noticed. The detraining period showed that, although strength parameters remained stable, swimming performance still improved.
Key pointsThis study investigated the effect of dry land strength training on sprint performance in young competitive swimmers.A combined strength and aerobic swimming training allow dry land strength developments in young swimmers.The main data can not clearly state that strength training allowed an enhancement in swimming performance, although a tendency to improve sprint performance due to strength training was noticed.The detraining period showed that, although strength parameters remained stable, swimming performance still improved.
PMCID: PMC3761739  PMID: 24149700
Children; combined training; detraining; hydrodynamics; cross training
3.  Biomechanical Analysis of the Swim-Start: A Review 
This review updates the swim-start state of the art from a biomechanical standpoint. We review the contribution of the swim-start to overall swimming performance, the effects of various swim-start strategies, and skill effects across the range of swim-start strategies identified in the literature. The main objective is to determine the techniques to focus on in swimming training in the contemporary context of the sport. The phases leading to key temporal events of the swim-start, like water entry, require adaptations to the swimmer’s chosen technique over the course of a performance; we thus define the swim-start as the moment when preparation for take-off begins to the moment when the swimming pattern begins. A secondary objective is to determine the role of adaptive variability as it emerges during the swim-start. Variability is contextualized as having a functional role and operating across multiple levels of analysis: inter-subject (expert versus non-expert), inter-trial or intra-subject (through repetitions of the same movement), and inter-preference (preferred versus non-preferred technique). Regarding skill effects, we assume that swim-start expertise is distinct from swim stroke expertise. Highly skilled swim-starts are distinguished in terms of several factors: reaction time from the start signal to the impulse on the block, including the control and regulation of foot force and foot orientation during take-off; appropriate amount of glide time before leg kicking commences; effective transition from leg kicking to break-out of full swimming with arm stroking; overall maximal leg and arm propulsion and minimal water resistance; and minimized energy expenditure through streamlined body position. Swimmers who are less expert at the swim-start spend more time in this phase and would benefit from training designed to reduce: (i) the time between reaction to the start signal and impulse on the block, and (ii) the time in transition (i.e., between gliding and leg kicking, and between leg-kicking and full swimming).
Key pointsSwimmers meet two main constraints during the start movement: travelling more distance in the air (to get less resistance) and rotate to enter properly in the water.Swim start is a sum of compromises in all parts of it, and swim-start expertise is distinct from swim stroke expertise corresponding to best ways to manage these compromises.Variability found is contextualized as having a functional role and operating across multiple levels of analysis.
PMCID: PMC3990873  PMID: 24790473
Biomechanics; expertise; performance; techniques; variability
4.  Preventing and Treating Lower Extremity Stress Reactions and Fractures in Adults 
Journal of Athletic Training  2006;41(4):466-469.
Reference/Citation: Rome K, Handoll HH, Ashford R. Interventions for preventing and treating stress fractures and stress reactions of bone of the lower limbs in young adults. Cochrane Database Syst Rev.20052:CD000450. Update from Gillespie WJ, Grant I. Interventions for preventing and treating stress fractures and stress reactions of bone of the lower limbs in young adults. Cochrane Database Syst Rev.20002: CD000450.
Clinical Question: Do evidence-based interventions exist for the prevention and treatment of stress reactions and stress fractures in young active adults?
Data Sources: This systematic review is an update of the original article, which was published in 2000. The authors conducted a literature review of computerized databases that included the Cochrane Musculoskeletal Injuries Group Specialized Register (April 2004), the Cochrane Central Register of Controlled Trials, MEDLINE (1966 to September 2004), EMBASE (1988 to 2004, week 36), CINAHL (1982 to 2004, September, week 1), Index to Theses (1990 to 2004), and Dissertation Abstracts (1990 to 2004). In addition, the authors searched the Current Controlled Trials at (June 2004, week 1) and the United Kingdom National Research Registrar at (to issue 1, 2004) for current or recently completed studies. They also reviewed the British Journal of Podiatry, International Journal of Podiatric Biomechanics, Physiotherapy, and the Australian Journal of Podiatric Medicine for relevant studies. Furthermore, they contacted the Medical Departments of Defense Forces in Europe and North America to identify unpublished or unlisted military studies. Reference lists of all identified studies and Cochrane reviews were also investigated. The computer search strategy included 61 separate entries and included such terms as stress fractures, stress reactions, shin splints, overuse, athletic injuries, cumulative trauma disorders, running, and randomized controlled trial. The 3 authors of this updated review independently selected new articles for inclusion. Furthermore, the 12 articles that were included in the original systematic review were also reevaluated to ensure they met the defined inclusion criteria.
Study Selection: To qualify for inclusion, studies had to be randomized or quasirandomized control trials, involve interventions to prevent or treat lower extremity stress reactions and fractures, and include physically active adults (adolescence to middle age) who were involved in athletics or military training. Clinical and radiographic (bone scan or x-ray) evidence of a lower extremity stress reaction or stress fracture was also required for inclusion of treatment-based studies. Specifically, skeletal overuse injuries are considered the result of a cumulative and repetitive process that produces initial microstructural changes or stress reactions that are identified by bone scans or magnetic resonance imaging but not conventional radiographs. If cumulative stresses continue, structural changes are visualized on radiographs and are referred to as stress fractures. In addition, research studies involving the treatment of medial tibial stress syndrome or shin splints were excluded. Desired outcome measures for treatment studies included return to training time, return to normal physical activity, functional performance, quality of life measures, resource management (eg, costs, health care visits, diagnostic procedures), adverse effects, and compliance.
The inclusion criteria for stress fracture prevention studies were similar, except that the authors did not have to provide radiographic evidence of a stress fracture or stress reaction. Prevention studies included a combination of the following outcome measures: occurrence and location of stress fracture, stratification of diagnosis, incidence of other lower limb injuries, complications and adverse effects of prevention techniques, resource management, and compliance with the prevention strategy.
Data Extraction: At least 2 reviewers independently extracted the demographic and outcome data from the newly identified studies, and 1 author verified the data and results from the 12 studies included in the 2000 Cochrane review. Inconsistencies from the original review and data from all new studies were also checked by an additional reviewer. All 3 reviewers then independently evaluated the quality of inclusion studies using a quality scoring scheme ( Table). The categories considered included randomization or group allocation (A), intention-to-treat analysis (B), examiner blinding (C), comparison of experimental and control groups at baseline (D), use of a placebo treatment (E), clearly defined subject inclusion and exclusion criteria (F), and methods of outcome assessments (G). Items A through F were scored from 0 to 2 and item G from 0 to 3, for a total “best” quality assessment score (QAS) of 15. Inconsistencies among reviewers' QAS scores were resolved by discussion and with the aid of a discrepancies form.
Main Results: Search criteria identified 24 new studies since the previous review, 8 of which fulfilled the inclusion criteria. In addition, 4 of the 12 studies included in the original 2000 review were excluded. Three were excluded as a result of insufficient indication of subject or group randomization or quasirandomization, and the fourth excluded study included subjects with the diagnosis of medial tibial stress syndrome. Overall, 16 studies were included.
The authors of 13 studies focused on prevention, and 3 groups evaluated the treatment of stress fractures and reactions. The average number of subjects for prevention and treatment studies, respectively, was 1091 (range = 206 to 3025) and 34 (range = 21 to 60). All 13 prevention studies involved military personnel who performed physical training over a 9-to-14–week period. Quality assessment scores for prevention studies ranged from 4 to 10 (mean score = 7). In 9 prevention studies, the effectiveness of insoles or orthoses was evaluated, and the QAS for these studies ranged from 4 to 9 (mean = 6.2). The investigators in 4 studies assessed “shock-absorbing” insoles or orthoses in shoes or boots versus a control (shoes or boots alone), and an additional 5 groups compared insoles and orthoses against one another. One study's authors also evaluated military training in a modified high-top shoe versus standard military boots (QAS = 8). Two groups assessed the influence of pre-exercise stretching (QAS = 8 and 9, respectively), and one investigated the effects of calcium supplementation (QAS = 10).
In none of the prevention studies were adequate randomization and concealment of treatment before group allocation (item A) accomplished, and the researchers in 3 studies randomized groups (team or platoon) instead of individual participants. Attrition rates exceeded 50% in 2 studies, and missing subjects' data were unaccounted for in the final analysis of 3 studies (item B, intention-to-treat analysis). Also, in only 2 of 13 studies were examiners blinded to group assignment (item C). Radiographic (bone scan or x-ray) evidence for diagnostic confirmation of a stress reaction or fracture was used in 12 studies. The method of diagnosis (item G) was based solely on clinical examination or a self-report questionnaire in 2 studies, and diagnostic methods were not described in 2 studies.
Overall fewer osseous stress injuries were reported in the experimental groups for all 4 studies comparing military personnel in “shock absorbing insoles” with controls (no insoles). However, none of these 4 studies demonstrated a statistically significant reduction in lower extremity overuse osseous injuries. In addition, statistically significant results were reported in only 1 of 5 studies that compared various orthoses and insoles. The authors reported a significant reduction in tibial stress fractures for soldiers wearing custom-made semirigid or soft-foot orthoses versus those wearing standard insoles (relative risk = 0.46, 95% confidence interval = 0.22 to 0.93). In a follow-up study, no significant difference in stress fracture rates was seen between subjects who wore custom-made semirigid orthoses and those who wore biomechanical soft orthoses, thus precluding the ability to identify one best design for stress fracture reduction. No significant stress fracture or lower extremity injury rate differences were seen between the control and experimental groups involved in lower extremity stretching studies. Participants taking calcium supplements did not demonstrate a significant reduction in stress fractures (tibial only) versus controls. The differences among the prevention studies prohibited pooling of the data and subsequent meta-analysis. Authors of all 3 treatment studies investigated the effects of a pneumatic ankle foot orthosis (Aircast Corp, Summit, NJ). Follow-up for outcome measures ranged from 78 days to 6 months. Two studies were conducted with military recruits, and the other was conducted with competitive and recreational athletes (n = 18, age range = 18 to 45 years). Treatment QASs ranged from 7/15 to 11/ 15, with an average score of 9.3/15. Proper randomization (item A) and evaluator blinding (item C) were confirmed in 1 of the 3 treatment studies. Data pooled from all 3 studies reached statistical significance for mean number of days until returning to full activities (weighted mean difference with brace versus without brace = −33.39 days, 95% confidence interval = −44.18 to −22.59 days).
Conclusions: Currently, no solid evidence-based interventions to prevent lower extremity stress reactions or fractures exist. Limited evidence suggests that “shock absorbing” insoles may reduce the overall incidence of lower extremity osseous injuries in military personnel. Unfortunately, research does not support the best design for inserts or footwear modifications. There is also insufficient evidence to determine if pre-performance stretching or calcium supplementation offers added protection from lower extremity osseous overuse injuries. Initial evidence supports the use of a pneumatic brace and early mobilization for the treatment of tibal stress reactions and fractures, but additional studies are required to validate these findings. Further investigation concerning the prevention and treatment of lower extremity stress fractures is needed and would assist researchers in establishing and clarifying evidence-based intervention guidelines. Future randomized control trials that clearly define (ie, provide clinical and radiographic evidence for) the diagnosis of a stress fracture or reaction, implement appropriate randomization, and use intervention and outcome measures (functional and performance measurements) that are appropriate for active adults would assist this ongoing and necessary process.
PMCID: PMC1748425  PMID: 17273474
athletic injuries; outcomes assessment
5.  Epidemiology of Injuries and Prevention Strategies in Competitive Swimmers 
Sports Health  2012;4(3):246-251.
Competitive swimmers are predisposed to musculoskeletal injuries of the upper limb, knee, and spine. This review discusses the epidemiology of these injuries, in addition to prevention strategies that may assist the physician in formulating rehabilitation programs for the swimmer following an injury.
Evidence Acquisition:
A literature search was performed by a review of Google Scholar, OVID, and PubMed articles published from 1972 to 2011.
This study highlights the epidemiology of injuries common to competitive swimmers and provides prevention strategies for the sports health professional.
An understanding of swimming biomechanics and typical injuries in swimming aids in early recognition of injury, initiation of treatment, and design of optimal prevention and rehabilitation strategies.
PMCID: PMC3435931  PMID: 23016094
competitive swimmer; injury; prevention; shoulder; knee; spine
6.  Biomechanical Considerations in the Competitive Swimmer’s Shoulder 
Sports Health  2010;2(6):519-525.
Competitive swimming has become an increasingly popular sport in the United States. In 2007, more than 250 000 competitive swimmers were registered with USA Swimming, the national governing body. The average competitive swimmer swims approximately 60 000 to 80 000 m per week. With a typical count of 8 to 10 strokes per 25-m lap, each shoulder performs 30 000 rotations each week. This places tremendous stress on the shoulder girdle musculature and glenohumeral joint, and it is why shoulder pain is the most frequent musculoskeletal complaint among competitive swimmers.
Evidence Acquisition:
Articles were obtained through a variety of medical search sources, including Medline, Google Scholar, and review articles from 1980 through January 2010.
The most common cause of shoulder pain in swimmers is supraspinatus tendinopathy. Glenohumeral instability and labral tears have also been reported, but a paucity of information remains regarding prevalence and treatment in swimmers.
Because of the great number of stroke repetitions and force generated through the upper extremity, the shoulder is uniquely vulnerable to injury in the competitive swimmer. Comprehensive evaluation should include the entire kinetic chain, including trunk strength and core stability.
PMCID: PMC3438875  PMID: 23015983
swimmer’s shoulder; swim strokes; biomechanics
7.  Risk Factors Associated With Shoulder Pain and Disability Across the Lifespan of Competitive Swimmers 
Journal of Athletic Training  2012;47(2):149-158.
The prevalence of shoulder pain among competitive swimmers is high, but no guidelines exist to reduce shoulder injuries. Elucidating differences between swimmers with and without shoulder pain can serve as a basis for the development of a program to prevent shoulder injury that might lead to pain and dysfunction.
To determine whether physical characteristics, exposure, or training variables differ between swimmers with and without shoulder pain or disability.
Cross-sectional study.
Multisite swimming centers.
Patients or Other Participants:
A total of 236 competitive female swimmers aged 8 to 77 years.
Data Collection and Analysis:
Participants completed the Penn Shoulder Score and underwent testing of core endurance, range of motion, muscle force production, and pectoralis minor muscle length and the Scapular Dyskinesis Test. Swimmers were grouped by age for analysis: ages 8 to 11 years (n = 42), 12 to 14 years (n = 43), 15 to 19 years (high school, n = 84), and 23 to 77 years (masters, n = 67). Comparisons were made between groups with and without pain and disability using independent t tests for continuous data and χ2 analyses and Fisher exact tests for categorical data.
Nine (21.4%) swimmers aged 8 to 11 years, 8 (18.6%) swimmers aged 12 to 14 years, 19 (22.6%) high school swimmers, and 13 (19.4%) masters swimmers had shoulder pain and disability. Differences that were found in 2 or more age groups between athletes with and without shoulder pain and disability included greater swimming exposure, a higher incidence of previous traumatic injury and patient-rated shoulder instability, and reduced participation in another sport in the symptomatic groups (P < .05). Reduced shoulder flexion motion, weakness of the middle trapezius and internal rotation, shorter pectoralis minor and latissimus, participation in water polo, and decreased core endurance were found in symptomatic females in single varying age groups (P < .05).
Female competitive swimmers have shoulder pain and disability throughout their lives. Given that exposure and physical examination findings varied between athletes with and without substantial pain and disability, a program to prevent shoulder injury that might lead to pain and dysfunction appears warranted and might include exposure reduction, cross-training, pectoral and posterior shoulder stretching, strengthening, and core endurance training.
PMCID: PMC3418126  PMID: 22488280
swimming; exposure variables; injury prevention
8.  Time course of changes in bilateral arm power of swimmers during recovery from injury using a swim bench. 
OBJECTIVES: There has been little research on the time course of recovery from injury in athletes. This is especially the case for recovery in arm power in injured swimmers. The purpose of this study was to compare the power output of the injured and non-injured arms of swimmers during recovery from injury by use of a maximal exercise test on a computer interfaced isokinetic swim bench. METHODS: Thirteen swimmers (five men and eight women; age 18.8 (3.2) years; stature 1.76 (0.05) m; body mass 61.7 (5.9) kg; mean (SD)) gave written informed consent and were recruited to this study throughout a three year period. All subjects had experienced non-aquatic soft tissue injury to their dominant-side shoulder or upper arm in the three months before participation, but had been allowed to return to swimming training. All of the subjects had injured their dominant arm and the mean time for absence from training was 3.7 (1.1) weeks. At return to training and at four, eight, and twelve weeks thereafter, subjects performed two all-out 30 second tests on the swim bench by simulating the swimming arm action. From these tests, peak power output (PPO), mean power output (MPO), and power decay (PD) for each arm during the 30 seconds of exercise could be determined by averaging the two tests. The differences between return to training and the four, eight, and twelve week periods were analysed using repeated measures analysis of variance with Tukey b post hoc test. RESULTS: The repeated testing showed 95% confidence intervals of +/- 11.4 W for PPO, +/- 9.5 W for MPO and +/- 0.5 for PD. When the swimmers returned to training the results showed that PPO was 179 (21.9) v 111 (18.1) W (P = 0.02), MPO was 122 (9.8) v 101 (8.8) W (P = 0.01), and PD was 2.5 (0.6) v 5.2 (1.9) (P = 0.001) for non-injured and injured arms respectively (all values mean (SEM)). There were similar differences at four weeks which disappeared after eight weeks, except for that of PPO which was still evident (187.3 (21.9) v 156.8 (18.1) W; P = 0.01). At 12 weeks there were no differences between the non-injured and injured arm on any of the indices of arm power (P > 0.05). CONCLUSIONS: These results suggest that, using the swim bench power test, differences in bilateral arm power output after injury persist for at least eight weeks after return to swimming training. These findings support the need for prolonged rehabilitation after such injury. This would best include physiotherapy and a training programme within which special consideration is given to the recuperation process.
PMCID: PMC1332522  PMID: 9298556
9.  Prevention and Treatment of Swimmer's Shoulder 
Swimmer's shoulder is a musculoskeletal condition that results in symptoms in the area of the anterior lateral aspect of the shoulder, sometimes confined to the subacromial region. The onset of symptoms may be associated with impaired posture, glenohumeral joint mobility, neuromuscular control, or muscle performance. Additionally, training errors such as overuse, misuse, or abuse may also contribute to this condition. In extreme cases, patients with swimmer's shoulder may have soft tissue pathology of the rotator cuff, long head of the biceps, or glenoid labrum. Physical therapists involved in the treatment of competitive swimmers should focus on prevention and early treatment, addressing the impairments associated with this condition, and analyzing training methods and stroke mechanics. The purpose of this clinical commentary is to provide an overview of the biomechanics of swimming, the etiology of the clinical entity referred to as swimmer's shoulder, and strategies for injury prevention and treatment.
PMCID: PMC2953356  PMID: 21522219
Swimmer's shoulder; injury prevention; rotator cuff
10.  Physiological, Biomechanical and Anthropometrical Predictors of Sprint Swimming Performance in Adolescent Swimmers 
The purpose of this study was to analyze the relationships between 100-m front crawl swimming performance and relevant biomechanical, anthropometrical and physiological parameters in male adolescent swimmers. Twenty five male swimmers (mean ± SD: age 15. 2 ± 1.9 years; height 1.76 ± 0.09 m; body mass 63.3 ± 10.9 kg) performed an all-out 100-m front crawl swimming test in a 25-m pool. A respiratory snorkel and valve system with low hydrodynamic resistance was used to collect expired air. Oxygen uptake was measured breath-by-breath by a portable metabolic cart. Swimming velocity, stroke rate (SR), stroke length and stroke index (SI) were assessed during the test by time video analysis. Blood samples for lactate measurement were taken from the fingertip pre exercise and at the third and fifth minute of recovery to estimate net blood lactate accumulation (ΔLa). The energy cost of swimming was estimated from oxygen uptake and blood lactate energy equivalent values. Basic anthropometry included body height, body mass and arm span. Body composition parameters were measured using dual-energy X-ray absorptiometry (DXA). Results indicate that biomechanical factors (90.3%) explained most of 100-m front crawl swimming performance variability in these adolescent male swimmers, followed by anthropometrical (45.8%) and physiological (45.2%) parameters. SI was the best single predictor of performance, while arm span and ∆La were the best anthropometrical and physiological indicators, respectively. SI and SR alone explained 92.6% of the variance in competitive performance. These results confirm the importance of considering specific stroke technical parameters when predicting success in young swimmers.
Key pointsThis study investigated the influence of different anthropometrical, physiological and biomechanical parameters on 100-m swimming performance in adolescent boys.Biomechanical factors contributed most to sprint swimming performance in these young male swimmers (90.3% of variability in performance), followed by anthropometrical (45.8%) and physiological (45.2%) parameters.Two selected variables (stroke index and stroke rate) explained 92.6% of the variance in competitive performance in these adolescent swimmers.
PMCID: PMC3761703  PMID: 24149633
oxygen uptake; stroke index; energy cost; front crawl
11.  Effectiveness of the Power Dry-Land Training Programmes in Youth Swimmers 
Journal of Human Kinetics  2012;32:77-86.
The aim of the study was to evaluate the effects of the dry-land power training on swimming force, swimming performance and strength in youth swimmers. Twenty six male swimmers, free from injuries and training regularly at least 6 times a week, were enrolled in the study and randomly assigned to one of two groups: experimental (n=14, mean age 14.0 ± 0.5 yrs, mean height 1.67±0.08 m and mean body mass 55.71 ±9.55 kg) and control (n=12, mean age 14.1 ± 0.5 yrs, mean height 1.61±0.11 m and mean body mass 49.07 ±8.25 kg). The experimental group took part in a combined swimming and dry-land power training. The control group took part in swimming training only. The training programmes in water included a dominant aerobic work in front crawl. In this research the experimental group tended to present slightly greater improvements in sprint performance. However, the stroke frequency insignificantly decreased (−4.30%, p>0.05) in the experimental group and increased (6.28%, p>0.05) in the control group. The distance per stroke insignificantly increased in the experimental group (5.98%, p>0.05) and insignificantly decreased in the control group (−5.36%, p>0.05). A significant improvement of tethered swimming force for the experimental group (9.64%, p<0.02) was found, whereas the increase was not statistically significant in the control group (2.86%, p>0.05). The main data cannot clearly state that power training allowed an enhancement in swimming performance, although a tendency to improve swimming performance in tethered swimming was noticed.
PMCID: PMC3590875  PMID: 23486353
ergometer; strength; tethered force; youth swimmers
12.  Comparison of lung volume in Greek swimmers, land based athletes, and sedentary controls using allometric scaling. 
OBJECTIVE: To compare lung volumes in a large cross sectional sample of Greek swimmers, land based athletes, and sedentary controls by means of allometric scaling. METHODS: Four hundred and fifty nine asymptomatic Greek children and young adults (age 10-21 years), including 159 swimmers, 130 land based athletes, and 170 sedentary controls, performed forced expiratory manoeuvres into a portable spirometer. Measurements included forced vital capacity, forced expiratory volume in one second (FEV1.0), and peak expiratory flow. Body mass and stature were also measured using standardised anthropometric techniques. RESULTS: Logarithmic transformations showed that in FEV1.0 was highly related to in stature in males and females (r = 0.93 and 0.86 respectively, P < 0.001) and were used to determine the exponent in an allometric equation which also included age and age. Resulting power functions, FEV1.0/stature, were 0.64 (0.18) litres/m2.69 and 0.33 (0.24) litres/m2.32 for males and females respectively (mean (SE)). The male and female swimming groups had larger FEV1.0 than both land based athletes and sedentary controls (one way analysis of variance, P < 0.001). In addition, male national standard swimmers (n = 38) had superior FEV1.0 in comparison with male non-national standard swimmers (n = 24; t test, P < 0.05). However, when years of swimming training was controlled for by analysis of covariance, the difference in FEV1.0 between the two groups was no longer evident. CONCLUSIONS: Swimmers have superior FEV1.0 independent of stature and age in comparison with both land based athletes and sedentary controls. In addition, male national standard swimmers have superior FEV1.0 independent of stature and age in comparison with male non-national standard swimmers. When years of training is controlled for, the difference in FEV1.0 between the two groups is no longer evident. This suggests that the years of swimming training and/or the earlier age at which training begins may have a significant influence on subsequent FEV1.0 and swimming performance. However, because of the cross sectional nature of this study, the results do not exclude genetic endowment as a major determinant of the superior lung volume observed in swimmers.
PMCID: PMC1332573  PMID: 9429014
13.  Can Blood Gas and Acid-Base Parameters at Maximal 200 Meters Front Crawl Swimming be Different Between Former Competitive and Recreational Swimmers? 
The aim of the present study was to ascertain whether maximal 200 m front crawl swimming strategies and breathing patterns influenced blood gas and acid-base parameters in a manner which gives advantage to former competitive swimmers in comparison with their recreational colleagues. Twelve former competitive male swimmers (the CS group) and nine recreational male swimmers (the RS group) performed a maximal 200 m front crawl swimming with self- selected breathing pattern. Stroke rate (SR) and breathing frequency (BF) were measured during the swimming test. Measures also included blood lactate concentration ([LA]) and parameters of blood acid-base status before and during the first minute after the swimming test. The CS group swam faster then the RS group. Both groups have similar and steady SR throughout the swimming test. This was not matched by similar BF in the CS group but matched it very well in the RS group (r = 0.89). At the beginning of swimming test the CS group had low BF, but they increased it throughout the swimming test. The BF at the RS group remained constant with only mirror variations throughout the swimming test. Such difference in velocity and breathing resulted in maintaining of blood Po2 from hypoxia and Pco2 from hypercapnia. This was similar in both groups. [LA] increased faster in the CS group than in the RS group. On the contrary, the rate of pH decrease remained similar in both groups. The former competitive swimmers showed three possible advantages in comparison to recreational swimmers during maximal 200 m front crawl swimming: a more dynamic and precise regulation of breathing, more powerful bicarbonate buffering system and better synchronization between breathing needs and breathing response during swimming.
Key pointsTraining programs for competitive swimmers should promote adaptations to maximal efforts.Those adaptations should include high and maximal intensity swims with controlled breathing frequency (taking breath every fourth, fifth, sixth or eighth stroke cycle for front crawl swimming).Such training will improve breathing regulation in order to impose a better synchronization between breathing needs and breathing response during maximal swimming.
PMCID: PMC3763334  PMID: 24150142
Swimming; freestyle; breathing; blood gas; acid-base status
14.  Descriptive Epidemiology of Collegiate Women's Softball Injuries: National Collegiate Athletic Association Injury Surveillance System, 1988–1989 Through 2003–2004 
Journal of Athletic Training  2007;42(2):286-294.
Objective: To review 16 years of National Collegiate Athletic Association (NCAA) injury surveillance data for women's softball and to identify potential areas for injury prevention initiatives.
Background: The NCAA Injury Surveillance System has tracked injuries in all divisions of NCAA softball from the 1988– 1989 to the 2003–2004 seasons. This report describes what was found and why the findings are important for the safety, enhancement, and continued growth of the sport.
Main Results: Across all divisions, preseason practice injury rates were more than double the regular-season practice injury rates (3.65 versus 1.68 injuries per 1000 athlete-exposures, rate ratio = 2.2, 95% confidence interval [CI] = 2.0, 2.4, P < .01). The rate of injury in a game was 1.6 times that in a practice (4.30 versus 2.67 injuries per 1000 athlete-exposures, rate ratio = 1.6, 95% CI = 1.5, 1.7). A total of 51.2% of game injuries resulted from “other-contact” mechanisms, whereas 55% of practice injuries resulted from noncontact mechanisms. In games, ankle ligament sprains and knee internal derangements accounted for 19% of injuries. Twenty-three percent of all game injuries were due to sliding, most of which were ankle sprains. In practices, ankle ligament sprains, quadriceps and hamstring strains, shoulder strains and tendinitis, knee internal derangements, and lower back strains (combined) accounted for 38% of injuries.
Recommendations: Ankle ligament sprains, knee internal derangements, sliding injuries, and overuse shoulder and low back injuries were among the most common conditions in NCAA women's softball. Preventive efforts should focus on sliding technique regardless of skill level, potential equipment changes, neuromuscular training programs, position-specific throwing programs, and mechanisms of low back injury. Further research is needed on the development and effects of these preventive efforts, as well as in the area of windmill-pitching biomechanics.
PMCID: PMC1941294  PMID: 17710178
athletic injuries; injury prevention; ankle injuries; knee injuries
A large percentage of swimmers report shoulder pain during their swimming career. Shoulder pain in swimmers has been attributed to duration of swim practice, total yardage, and break down in stroke technique. Rehabilitation programs are generally land‐based and cannot adequately address the intricacies of the swimming strokes. Return to swimming protocols (RTSP) that address progression of yardage are scarce, yet needed. The purpose of this clinical commentary is to familiarize the clinician with the culture and vernacular of swimming, and to provide a suggested yardage based RTSP for high school and collegiate level swimmers.
Level of Evidence:
PMCID: PMC4196335  PMID: 25328833
Freestyle stroke; technique; yardage
16.  Combined Strength and Endurance Training in Competitive Swimmers 
A combined intervention of strength and endurance training is common practice in elite swimming training, but the scientific evidence is scarce. The influences between strength and endurance training have been investigated in other sports but the findings are scattered. Some state the interventions are negative to each other, some state there is no negative relationship and some find bisected and supplementary benefits from the combination when training is applied appropriately. The aim of this study was to investigate the impact of a combined intervention among competitive swimmers. 20 subjects assigned to a training intervention group (n = 11) or a control group (n = 9) from two different teams completed the study. Anthropometrical data, tethered swimming force, land strength, performance in 50m, 100m and 400m, work economy, peak oxygen uptake, stroke length and stroke rate were investigated in all subjects at pre- and post-test. A combined intervention of maximal strength and high aerobic intensity interval endurance training 2 sessions per week over 11 weeks in addition to regular training were used, while the control group continued regular practice with their respective teams. The intervention group improved land strength, tethered swimming force and 400m freestyle performance more than the control group. The improvement of the 400m was correlated with the improvement of tethered swimming force in the female part of the intervention group. No change occurred in stroke length, stroke rate, performance in 50m or 100m, swimming economy or peak oxygen uptake during swimming. Two weekly dry-land strength training sessions for 11 weeks increase tethered swimming force in competitive swimmers. This increment further improves middle distance swimming performance. 2 weekly sessions of high- intensity interval training does not improve peak oxygen uptake compared with other competitive swimmers.
Key pointsTwo weekly sessions of dry land strength training improves the swimming force.Two weekly sessions of high-intensity endurance training did not cause improved endurance capacity.It may seem that dry land strength training can improve middle distance performance.
PMCID: PMC3763280  PMID: 24149998
Oxygen consumption; muscle strength; metabolic efficiency
17.  Prevalence of Freestyle Biomechanical Errors in Elite Competitive Swimmers 
Sports Health  2014;6(3):218-224.
Poor freestyle stroke biomechanics is a suggested risk factor for shoulder pain and pathology, but this has not been proven in biomechanical or clinical studies. Furthermore, the prevalence of these theoretical errors has not been identified, which would help coaches, athletic trainers, and researchers determine the most appropriate errors to focus on and develop interventions.
The majority of swimmers will present with at least 1 freestyle stroke error.
Study Design:
Cross-sectional study.
Level of Evidence:
Level 4.
Stroke biomechanics for 31 swimmers from a collegiate swimming team were captured using underwater/above-water cameras. Each video was evaluated for biomechanical errors: a dropped elbow during the pull-through phase, a dropped elbow during the recovery phase, an eyes-forward head-carrying angle, incorrect hand position during hand entry, incorrect hand entry angle, incorrect pull-through pattern, and inadequate body roll. Error prevalence was calculated, and relationships among the errors were evaluated using chi-square statistics.
A dropped elbow during the pull-through phase (61.3%) and a dropped elbow during the recovery phase (53.2%) had the highest prevalence. A dropped elbow during the recovery phase was significantly associated with a thumb-first hand entry angle (P = 0.027) and incorrect hand entry position (P = 0.009). An eyes-forward head-carrying angle was associated with an incorrect pull-through pattern (P = 0.047).
Biomechanical errors potentially detrimental to the shoulder are prevalent among swimmers. Many of the errors were interrelated, suggesting that one error may lead to other errors.
Clinical Relevance:
These errors highlight the need for proper stroke instruction and evaluation to decrease the risk of shoulder injury in competitive swimmers.
PMCID: PMC4000476  PMID: 24790691
swimming; biomechanics; shoulder injury; injury prevention
18.  Swimming Stroke Mechanical Efficiency and Physiological Responses of 100-m Backstroke with and without the use of paddles 
Journal of Human Kinetics  2014;40:171-180.
The use of swimming aids during training contributes to greater swimming efficiency by the improvement of the swimming specific power of the athlete. The purpose of this study was to compare the swimming stroke technical characteristics and the physiological responses of swimming 100-m backstroke, with and without the use of paddles at maximum and sub-maximum intensities at the same swimming speed. Eight swimmers competing at the national level participated in this study. The measurements took place at 4 different sessions. At every session, each participant swam individually one 100-m backstroke swimming trial with or without paddles at the same speed and two levels of intensity (100% and 85% of maximum speed). The results revealed lower stroke length, greater stroke number and gliding length without the use of swimming paddles at both intensities. Blood lactate concentration (10.03±2.96 vs. 5.85±2.23 mmol/l) and Rating of Perceived Exertion (17.43±2.07 vs. 12±2.82) were greater without the use of swimming paddles only at 100% of maximum speed. Thus, swimming backstroke with paddles compared to unaided swimming, at a similar speed, showed a greater efficiency at maximal but not at sub-maximal intensity.
PMCID: PMC4096093  PMID: 25031685
swimming; training aids; stroke length; stroke number; gliding length; blood lactate
19.  The Backstroke Swimming Start: State of the Art 
Journal of Human Kinetics  2014;42:27-40.
As sprint swimming events can be decided by margins as small as .01 s, thus, an effective start is essential. This study reviews and discusses the ‘state of the art’ literature regarding backstroke start biomechanics from 23 documents. These included two swimming specific publications, eight peer-reviewed journal articles, three from the Biomechanics and Medicine in Swimming Congress series, eight from the International Society of Biomechanics in Sports Conference Proceedings, one from a Biomechanics Congress and one academic (PhD) thesis. The studies had diverse aims, including swimmers’ proficiency levels and data collection settings. There was no single consensus for defining phase descriptions; and kinematics, kinetics and EMG approaches were implemented in laboratory settings. However, researchers face great challenges in improving methods of quantifying valid, reliable and accurate data between laboratory and competition conditions. For example, starting time was defined from the starting signal to distances as disparate as ∼5 m to 22.86 m in several studies. Due to recent rule changes, some of the research outcomes now refer to obsolete backstroke start techniques, and only a few studies considered the actual international rules. This literature review indicated that further research is required, in both laboratory and competition settings focusing on the combined influences of the current rules and block configuration on backstroke starting performances.
PMCID: PMC4234766  PMID: 25414737
Biomechanics; dorsal starts; starting technique; starting variant; literature review
20.  Arthroscopic Capsular Plication in the Treatment of Shoulder Pain in Competitive Swimmers 
HSS Journal  2010;6(2):145-149.
Shoulder pain is a common and difficult problem in competitive swimmers due to cumulative loads from repetitive overhead motion. Capsular laxity has been implicated as a potential etiology for shoulder pain in competitive swimmers. No study has examined the role of capsular plication in addressing recurrent shoulder pain in competitive swimmers. The purpose of this study is to retrospectively describe our series of competitive swimmers treated with arthroscopic capsular plication with a primary outcome of return to competitive swimming. Eighteen shoulders in 15 patients underwent arthroscopic capsular plication from 2003 to 2007. Patients were contacted at an average follow-up of 29 months (range, 8–42) and a swimming history, American Shoulder and Elbow (ASES) scores, and L'Insalata scores were obtained. At time of surgery, all patients demonstrated laxity under examination under anesthesia. All patients had a positive drive-through sign. Eighty percent (12/15) of patients returned to competitive swimming although only 20% (3/15) were able to return to their pre-injury training regimen volume. All patients subjectively reported improved pain after surgery. The average ASES score was 78 ± 16 (average, standard deviation). The average L'Insalata score was 82 ± 11. Although our results demonstrate that arthroscopic capsular plication has utility in the treatment of shoulder pain in swimmers who have failed non-operative treatment, the inability of some athletes to return to pre-injury training volume illustrates the difficult nature of shoulder pain in swimmers.
Level of Evidence: Retrospective case series, Level IV
PMCID: PMC2926370  PMID: 21886527
shoulder laxity; shoulder instability; shoulder pain; swimming; arthroscopic capsular plication
21.  The effects of course length on freestyle swimming speed in elite female and male swimmers – a comparison of swimmers at national and international level 
SpringerPlus  2013;2:643.
Freestyle swimming performance over 50 m, 100 m, 200 m, 400 m, 800 m and 1,500 m was compared on short (25 m) and long (50 m) course for 92,196 national swimmers (i.e. annual high score list Switzerland) and 1,104 international swimmers (i.e. finalists FINA World Championships) from 2000 to 2012. National and international swimmers of both sexes were on average 2.0 ± 0.6% faster on short than on long course. Sex-related differences in swimming speed were greater on short than on long course for international and national swimmers from 50 m to 800 m. Freestyle swimming performance improved across years for international swimmers in both short- and long-course whereas only male national swimmers were able to improve on short and long course events except for short course events on 800 m and 1,500 m. Performance in national women competing in short and long course events showed only improvements on 50 m, 100 m and 1,500 m across years. The sex-related differences in freestyle swimming performance showed no change for international swimmers. For national swimmers, the sex-related differences in freestyle swimming performance increased over time in long course from 50 m to 800 m, but decreased for 1,500 m. In conclusion, elite female and male freestyle swimmers at national and international level were about 2% faster on 25 m compared to 50 m course. During the 2000–2012 period, international as well as national swimmers (i.e. for national level predominantly men) improved freestyle swimming performance in both long and short course. More vigorous and optimized training programs focused on muscular force production in combination with efficient swimming skills might close the performance gap between elite swimmers at national level and FINA finalists. Further research especially including effects of anthropometric, biomechanical, and physiological factors is required to fully understand the effects of course length on freestyle swimming performance, and to determine whether course length has similar effects on other swim styles.
PMCID: PMC3862862  PMID: 24349949
Athlete; Sex; Endurance; Performance
22.  Searching for Criteria in Evaluating the Monofin Swimming Turn from the Perspective of Coaching and Improving Technique 
This study aims to analysise the selected kinematic parameters of the monofin swimming turn. The high complexity of performing turns is hindered by the large surface of the monofin, which disturbs control and sense of the body in water. A lack of objective data available on monofin swimming turns has resulted in field research connected with the specification of parameters needed for the evaluation of the technique. Therefore, turns observed in elite swimmers contain underlying conclusions for objective criteria, ensuring the highest level of coaching and the improving of turns in young swimmers. Six, high level, male swimmers participated in the study. The subject of the analysis was the fastest turn, from one out of three trial turns made after swimming a distance of 25 m. Images of the turns were collected from two cameras located under water in accordance with the procedures of the previous analyses of freestyle turns. The images were digitized and analysed by the SIMI®- Movement Analysis System. The interdependency of the total turn time and the remaining recorded parameters, constituted the basis for analysis of the kinematic parameters of five turn phases. The interdependency was measured using r- Pearson’s correlation coefficients. The novel character of the subject covered in this study, forced interpretation of the results on the basis of turn analyses in freestyle swimming. The results allow for the creation of a diagram outlinig area of search for an effective and efficient monofin swimming turn mechanism. The activities performed from the moment of wall contact until the commencement of stroking seem to be crucial for turn improvement. A strong belief has resulted that, the correct monofin swimming turn, is more than just a simple consequence of the fastest performance of all its components. The most important criteria in evaluating the quality of the monofin swimming turn are: striving for the optimal extension of wall contact time, push-off time and glide time.
Key pointsShort time and large surface of the monofin additionally hinders complexity of the turn performance by disturbance in sensing and controlling body in water. Availability of no objective data on monofin swimming turns resulted in research in the field connected with specifying parameters needed for the technique evaluation.Correct turn technique may help to improve swimming race results.The diagram constructed on the basis of the interdependency of the total turn time and the remaining recorded kinematic parameters should establish the areas of searching for mechanism of effective and efficient monofin swimming turn.The most crucial, from the coaching and improving point of view, seem to be activities which take place from the moment of feet wall contact till the first propulsive movements. Therefore, the high quality of the monofin swimming turn technique is not just a simple consequence of the fastest performance of all its component parts.The most important criteria of the quality in the monofin swimming turn technique are: striving for extending in the optimum scope of wall contact time, the time of the push-off phase and the glide time.
PMCID: PMC3763354  PMID: 24150136
Monofin; turn; kinematics; technique evaluation
23.  Time to Exhaustion at the VO2max Velocity in Swimming: A Review 
Journal of Human Kinetics  2012;32:121-134.
The aim of this study was to present a review on the time to exhaustion at the minimum swimming velocity corresponding to maximal oxygen consumption (TLim-vVO2max). This parameter is critical both for the aerobic power and the lactate tolerance bioenergetical training intensity zones, being fundamental to characterize it, and to point out its main determinants. The few number of studies conducted in this topic observed that swimmers were able to maintain an exercise intensity corresponding to maximal aerobic power during 215 to 260 s (elite swimmers), 230 to 260 s (high level swimmers) and 310 to 325 s (low level swimmers), and no differences between genders were reported. TLim-vVO2max main bioenergetic and functional determinants were swimming economy and VO2 slow component (direct relationship), and vVO2max, velocity at anaerobic threshold and blood lactate production (inverse relationship); when more homogeneous groups of swimmers were analysed, the inverse correlation value between TLim-vVO2max and vVO2max was not so evident. In general, TLim-vVO2max was not related to VO2max. TLim-vVO2max seems also to be influenced by stroking parameters, with a direct relationship to stroke length and stroke index, and an inverse correlation with stroke rate. Assessing TLim-vVO2max, together with the anaerobic threshold and the biomechanical general parameters, will allow a larger spectrum of testing protocols application, helping to build more objective and efficient training programs.
PMCID: PMC3590877  PMID: 23486651
bioenergetics; biomechanics; aerobic power; time limit; training
24.  Analysis of Drafting Effects in Swimming Using Computational Fluid Dynamics 
The purpose of this study was to determine the effect of drafting distance on the drag coefficient in swimming. A k-epsilon turbulent model was implemented in the commercial code Fluent® and applied to the fluid flow around two swimmers in a drafting situation. Numerical simulations were conducted for various distances between swimmers (0.5-8.0 m) and swimming velocities (1.6-2.0 m.s-1). Drag coefficient (Cd) was computed for each one of the distances and velocities. We found that the drag coefficient of the leading swimmer decreased as the flow velocity increased. The relative drag coefficient of the back swimmer was lower (about 56% of the leading swimmer) for the smallest inter-swimmer distance (0.5 m). This value increased progressively until the distance between swimmers reached 6.0 m, where the relative drag coefficient of the back swimmer was about 84% of the leading swimmer. The results indicated that the Cd of the back swimmer was equal to that of the leading swimmer at distances ranging from 6.45 to 8. 90 m. We conclude that these distances allow the swimmers to be in the same hydrodynamic conditions during training and competitions.
Key pointsThe drag coefficient of the leading swimmer decreased as the flow velocity increased.The relative drag coefficient of the back swimmer was least (about 56% of the leading swimmer) for the smallest inter-swimmer distance (0.5 m).The drag coefficient values of both swimmers in drafting were equal to distances ranging between 6.45 m and 8.90 m, considering the different flow velocities.The numerical simulation techniques could be a good approach to enable the analysis of the fluid forces around objects in water, as it happens in swimming.
PMCID: PMC3763353  PMID: 24150135
Training; human body; drag; tandem; finite element modeling
25.  Anterior Cruciate Ligament Injury Prevention Training in Female Athletes 
Sports Health  2012;4(1):36-46.
Many anterior cruciate ligament (ACL) injury prevention training programs have been published, but few have assessed the effects of training on both ACL injury rates and athletic performance tests.
To determine if ACL injury prevention programs have a positive influence on both injury rates and athletic performance tests in female athletes.
Data sources:
In August 2011, a search was conducted (1995–August 2011) of the PubMed, Science Direct, and CINAHL databases.
Study selection:
Selected studies determined the effect of ACL intervention training programs on ACL incidence rates (determined by athlete-exposures) and athletic performance tests, such as isokinetic strength, vertical jump height, speed, agility, and dynamic balance. Because no single article contained both criteria, investigations were cross-referenced to obtain data on both factors from the same training programs.
Data extraction:
The authors reviewed the selected studies for cohort population numbers, age, sports, duration of study, program components, duration of training, number of athlete-exposures, ACL injury incidence rates, and results of athletic performance tests.
Initially, 57 studies were identified that described 42 ACL injury prevention training programs. Of these, 17 studies that investigated 5 programs met the inclusion criteria. Two programs significantly reduced ACL injury rates and improved athletic performance tests: Sportsmetrics and the Prevent Injury and Enhance Performance program (PEP). Sportsmetrics produced significant increases in lower extremity and abdominal strength, vertical jump height, estimated maximal aerobic power, speed, and agility. Prevent Injury and Enhance Performance significantly improved isokinetic knee flexion strength but did not improve vertical jump height, speed, or agility. The other 3 programs (Myklebust, the “11,” and Knee Ligament Injury Prevention) did not improve both ACL injury rates and athletic performance tests.
Only the Sportsmetrics and PEP ACL intervention training programs had a positive influence on injury reduction and athletic performance tests.
PMCID: PMC3435901  PMID: 23016067
anterior cruciate ligament; injury prevention; athletic performance tests

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