Search tips
Search criteria 


Logo of nihpaAbout Author manuscriptsSubmit a manuscriptHHS Public Access; Author Manuscript; Accepted for publication in peer reviewed journal;
J Aging Phys Act. Author manuscript; available in PMC 2010 May 26.
Published in final edited form as:
J Aging Phys Act. 2009 July; 17(3): 257–271.
PMCID: PMC2877134

Strength and Speed Training for Elders With Mobility Disability


The purpose of this study was to pilot test a function-focused exercise intervention consisting of strength and gait-speed training in elders with reduced walking speed, decreased walking endurance, and functional impairment. Twelve participants, 77.2 years old (± 7.34), whose usual gait speed was <0.85 m/s, with walking endurance of <305 m in 5 min, and who were functionally impaired participated in a moderate-intensity exercise intervention. The training occurred 3 times per week, 75 min per session, for 3 months and combined 4 weeks of gait-speed training, walking exercise, and functional strengthening. The participants demonstrated mean usual gait speeds (≥1.0 m/s), endurance (≥350 m), and functional ability (≥10 score on performance battery) that were within normal limits after 12 weeks of training. Fastest gait speed (≥1.5 m/s) and muscle strength also improved significantly. Improvements were maintained during follow-up testing after 3–6 months. In summary, a 12-week intervention for frail, mobility-disabled participants led to improvements in walking, function, and strength.

Keywords: aging, gait, treadmill, energy costs

Loss of gait speed is one of the main changes in walking as people age (Bohannon, 1997; Hageman & Blanke, 1986; Larish, Martin, & Mungiole, 1988; Maki, 1997; Nigg, Fisher, & Ronsky, 1994, Okuzumi et al., 1995). Self-selected, usual walking speeds for well, noncompromised individuals 65 years of age or older are 1.0 m/s or above (Bohannon). The average usual walking speed for 70-year-olds has been reported as 1.17 ± 0.17 m/s for women and 1.33 ± 0.17 for men (Bassey, Bendall, & Pearson, 1988). Age-related reduction in walking speed has been reported as being 12–16% annually after the sixth decade (Judge, Whipple, & Wolfson, 1994). Declines in gait speed correlate with increasing disability among elders and might be a component of preclinical disability (Fried, Herdman, Kuhn, Rubin, & Turano, 1991; Guralnik et al., 2000).

General conditioning and strengthening exercises might be ineffective if not sufficiently intense or targeted on each participant’s specific impairments. Several researchers have reported that greater improvements were possible if the corresponding interventions were more precisely targeted on the modifiable risk factors of individuals (Maki, 1997; Rubenstein & Josephson, 1990; Tinetti, Baker, & McAvay, 1994). Older persons’ functional mobility performance and independence can be improved by enhancing lower extremity muscle function (Chandler, Duncan, Kochersberger, & Studenski, 1998; Fiatarone et al., 1990, 1994; Judge, Underwood, & Gennosa, 1993; McMurdo & Rennie, 1993; Sauvage et al., 1992). Improvements in gait speed are associated with improvements in lower extremity muscle strength and increased function (Binder et al., 2002). Many studies have investigated the strength–function relationship using different tasks in elders (Bendall, Bassey, & Pearson, 1989; Brown, Sinacore, & Host, 1995; Daubney & Culham, 1999; Rantanen, Era, & Heikkinen, 1994; Rantanen et al., 1998). In addition, studies have demonstrated that exercise, even low-intensity exercise, can improve gait speed in elders (Brown et al., 2000; King et al., 2002; Judge et al., 1993; Lord et al., 1996). Most of these studies were conducted with individuals without slowed normal speed. A study by Chandler and Hadley (1996) suggested that the effects of strength training on the timed walking test are only evident when gait speed is habitually below 1 m/s. Few exercise-intervention studies have included a community-dwelling population with gait speeds below this level. Judge (2003) also suggested that traditional resistance-training approaches using seated exercise with ankle weights might not have sufficient training specificity to improve measures of physical function such as stair climbing, chair rise, or gait speed. No study has included specific gait-speed training in combination with a function-focused strength-training intervention for mobility-disabled elders.

We conducted a pilot study of an exercise intervention that combines function-focused lower extremity strength training with an innovative program of gait-speed training for individuals 70 years of age or older who demonstrated a mobility disability, as characterized by a usual gait speed of <0.85 m/s and/or gait endurance of <305 m during a 5-min walk (Murphy, Olson, Protas, & Overby, 2003).



Twelve participants who were recruited from the community participated in the exercise training (2 men, 10 women; age 77.2 ± 7). A walking speed less than 0.85 m/s or a 5-min-walk distance less than 305 m was used to select participants who met the criteria for mobility disability. These cutoff points (speed or distance) were chosen based on the highest combined sensitivity and specificity values developed for fall risk by Murphy et al. (2003). In addition, only participants with a Short Physical Performance Battery (SPPB) score of ≤9 were included, to select participants who were functionally impaired (Guralnik et al., 1994). We excluded participants who had cognitive impairment as demonstrated by a score ≤23 on the Mini-Mental State Exam (Folstein, Folstein, & McHugh, 1975), were dependent in more than one activity of daily living (Katz, Ford, Moskowitz, Jackson, & Jaffee, 1963), had any medical contraindication to exercise (such as recent heart attack, abnormal stress test), had a lower extremity amputation, had a history of hip- or knee-joint replacement or repaired fractured hip, or had Parkinson’s disease requiring antiparkinsonian medication. The exclusion of prior lower extremity orthopedic and neurologic conditions was to reduce situations that might attenuate the response to the intervention. Participants currently enrolled in rehabilitation or an aerobic-exercise program were also not included. All participants provided written informed consent as approved by the institutional review board of the University of Texas Medical Branch.


Mobility-disabled participants engaged in a task-specific, function-focused intervention consisting of lower extremity strength training and walking exercise combined with speed training on a treadmill. Training occurred in a group session three times per week, 75 min each session, for 3 months.

Exercise Intervention

The first 15 min of exercise consisted of a warm-up activity of walking around an indoor track at a slow pace of low intensity, followed by 5- to 10-s bouts of fastest walking interspersed with standing rests and a 5-min walk of moderate intensity (Borg ratings of perceived exertion 12–14; (Borg, 1982). A 60-min progressive resistance-exercise period followed the warm-up, consisting primarily of closed kinetic chain exercises using body weight as resistance for all major muscle groups of the lower extremity. This exercise intervention was modified from exercise interventions suggested by Olson, Wang, and Protas (2001); Protas et al. (2001); and King et al. (2002). Exercises were selected to include function-focused activities, such as standing from a chair or the floor and stepping up, that are specific to tasks commonly performed in daily life. Intensity was increased by the number of repetitions, by performing unilateral activities, or by adding weight to vests (Table 1). The remaining 15 min of the 75 min were used for rest as needed throughout the exercise session.

Table 1
Function-Focused Exercise Intervention

Speed Training

Participants underwent an exercise-tolerance test in the Division of Cardiology to screen for normal cardiovascular responses to exercise before undergoing speed training. The speed-training approach was reported by Pohl, Mehrholz, Ritschel, and Ruckriem (2002) as a method to increase gait speed in older individuals after a stroke. The participants were placed in a harness attached to a standing frame over the treadmill for safety and in case of a fall (TreadSafely, Health Solutions, Inc., Clear Lake, TX). Each participant’s fastest gait speed was noted from the preliminary gait-speed test and designated as S1 for the first trial. The treadmill speed was increased over 1–2 min to that speed, and the participant walked at that speed for 10 s. The participant was allowed a short rest of 1–2 min before beginning the next trial. The speed of this trial was increased another 10% over S1. The speed continued to be increased each trial by another 10% over the previous trial for five trials, unless the participant was unable to maintain the speed. In this case, the speed from the previous trial was maintained. The next session started with the fastest speed from the previous session. To ensure that the participants were properly conditioned before beginning this training, the speed training occurred during the last 4 weeks of training only.


If a participant missed more than three consecutive exercise sessions for medical or other reasons, the participant was dropped from the study. If an occasional session was missed, the participant was allowed the make up the session until a total of 36 training sessions had occurred before posttesting.


Participants were tested for gait speed, gait endurance, function, and lower extremity muscle strength. Testing occurred 1 week preintervention, after 6 and 12 weeks of intervention, and at follow-up (3–6 months) for gait speed, 5-min-walk distance, and function. Oxygen costs and muscle strength were only tested before and after 12 weeks of intervention. Demographic information, medical history, medications taken, and level of depression were also collected at the beginning of the study.

Gait Speed

An instrumented walkway (GaitRite, CIR Systems, Havertown, PA) was used to measure gait speed. Each participant’s leg length was measured from the greater trochanter to the lateral malleolus and entered into the system along with age, gender, height, and weight. The participant was given verbal directions and asked to step on the end of the gait mat. Participants were instructed to walk at their usual gait speed. There were two consecutive trials, and participants could rest between trials if necessary. The two trials were averaged to determine self-selected, usual gait speed. After a short rest, the participants were asked to walk at their fastest safe speed. Again, two trials were conducted and averaged to determine fastest speed. This test has been found to be reliable for repeated tests on individuals with and without neurologic deficits (Cutlip, Mancinelli, Huber, & DiPasquale, 2000; McDonough, Batavia, Chen, Kwon, & Ziai, 2001; Urquhart, Morris, & Iansek, 1999). The primary variables of interest were usual and fastest gait speed (m/s). A cutoff score for usual gait speed of ≤0.85 m/s has been identified as being specific and sensitive to elders who fall (Murphy et al., 2003).

Gait Endurance

The 5-min-walk test was used to assess gait endurance by recording the distance walked during a 5-min period (Protas, 1997). Stanley and Protas (1991) have reported that, in elderly women, the 5-min walk provided moderately better estimates of maximal exercise performance than a 3-min walk. The 5-min-walk test distance has excellent test–retest reliability (r = .92; Peloquin, Gauthier, Bravo, Lacombe, & Billiare, 1998) and responsiveness (Peterson et al., 1993; Price, Hewett, Kay, & Minor, 1988). Participants were asked to walk as far and fast as possible in 5 min on an indoor circular track. Each participant was accompanied by a tester who was timing the walk with a stopwatch and using a wheeled measuring device to record the distance (MeterMaster Measuring Wheel). A cutoff score of 305 m has been identified as being sensitive and specific for fall detection in elders (Murphy et al., 2003).

Gait Energy Costs

Before beginning the walk test, each participant was fitted with a portable gas analyzer, a facemask, and a chest-band heart-rate transmitter. Samples of oxygen consumption (VO2) were recorded every 20 s, and three recordings were averaged to obtain the amount of oxygen consumed for each minute (Medical Graphics model VO2000, Minneapolis, MN). Values for the last 2 min were used to ensure a steady state for VO2. These values were averaged and recorded in milliliters of O2 per kilogram of body weight per minute walked (ml O2 · kg−1 · min−1). The oxygen consumed per meter walked, the gait energy cost (C), was also calculated. C was obtained by dividing the average VO2 for the last 2 min by the average number of meters walked per minute during the last 2 min of the walk test (total distance divided by 2). C was recorded in ml O2 · kg−1 · m−1. C has been shown to be a reliable measure during walking in healthy normal and older individuals (Cunha, Henson, Wankadia, & Protas, 2003; Cunha, Henson, et al., 2003).

Muscle Strength

Dynamic concentric knee-extensor and knee-flexor strength were determined for each leg as the maximal load a participant could lift a single repetition with proper form through a full range of motion (one-repetition maximum [1-RM]). All tests were unilateral. Participants were familiarized with the testing procedure to ensure that a maximum value was obtained. They were instructed about proper breathing and lifting techniques and warmed up with stretching exercises of the lower limbs followed by small loads on the resistance apparatus. An initial weight was chosen that was estimated to represent approximately 80% of the participant’s 1-RM and was progressively increased until the participant could not, on at least two attempts, move the lever arm through the full range of motion. To minimize the effects of fatigue, 1 min of rest was allowed between attempts, and 3–5 min between each movement. A physical therapist supervised all strength testing. Ankle plantar-flexor strength was tested by asking the participant, standing on one lower extremity, to rise onto the toes and back down as many times as possible in 30 s. The participant was allowed to hold onto a chair lightly to keep his or her balance (Lunsford & Perry, 1995). The number of repetitions was recorded. This measure has been shown to be sensitive in exercise interventions in frail elders (Chandler, Duncan, & Studenski, 1997).


To capture aspects of mobility function other than gait, we also used a timed step test, a timed floor transfer, and the SPPB. For the timed step test, the participant was asked to step up onto and down from an 8.8-cm step as fast as possible for five consecutive steps while being timed by a tester with a stopwatch. This test was scored as the number of steps per second, so better performance is reflected as a higher number. For the floor transfer, the participant was asked to move from complete standing down to a long sitting position on a mat and back up to complete standing. A chair was placed nearby, and the participant was told that it could be used for support if needed during this task. The inverse of this value was used (1 transfer/x seconds), so higher scores reflect better performance. These variables discriminate between elders who fall and those who do not report falls and between elders who do not report mobility disability and those who do (Murphy et al., 2003; Wang, Olson, & Protas, 2005). The SPPB (Guralnik et al., 2000, 1994) included a timed test of five chair stands, a timed 4-m walk, and a timed tandem or semitandem stand. Each of the three tests was scored on a 5-point ordinal scale from 0 to 4, with 4 being the best performance. These scores are summed for a final score ranging from 0 to 12. Scores of 10 or lower have been used to define elders with lower extremity disabilities (Bean et al., 2004).

Statistical Analysis

Means and standard deviations were calculated for pretraining, after 6 and 12 weeks of training, and at follow-up and compared with an analysis of variance with repeated measures for time. If a significant F ratio resulted, post hoc comparisons with paired t tests were performed between baseline and 6 and 12 weeks and follow-up, and between the 12-week and follow-up values. We selected an α level of .05 with a Bonferroni correction (.05/4 = .013). Variables measured twice (oxygen costs and strength) were compared with paired t tests.


Twelve participants engaged in the exercise training (2 men, 10 women; age 77.2 ± 7; MMSE 27.1 ± 4; Geriatric Depression scale 9.3 ± 4.8; SF 36 69.4% ± 10.5%; comorbidity 5.6 ± 1; number of medications 3.8 ± 3; Table 2). Nine completed the 12 weeks of training. Three participants dropped after 4, 7, and 8 weeks, respectively. The participant who dropped after 4 weeks was diagnosed with lung cancer and dropped the study to undergo treatment. This participant was unavailable for any further testing. The participant who dropped out after 7 weeks developed a lung infection before dropping out and subsequently died. The participant who dropped out after 8 weeks had a 45-min drive and had a transportation problem. All participants who completed the exercise training initially demonstrated mobility disabilities at the baseline but had mean usual gait speeds and 5-min-walk distance values that were within normal limits after 12 weeks of training (Table 3 and Figure 1). Fastest gait speed also improved significantly. Walking efficiency as measured by O2 costs per meter walked did not change, although participants were walking farther and faster after the training. Improvements in strength and the other measures of function also occurred. Seven of the 9 participants were retested 3–6 months after the training ended. The range of the follow-up period varied depending on the availability of the participants, but the average was 5 months. Improvements in usual and fastest gait speed, gait endurance, and the functional measures of timed chair stands and the timed step test were maintained at follow-up. After completing the training, participants reported that they could continue many of the exercises at home and that they walked on 3–7 days/week. Several participated in senior exercise classes weekly. None of the participants had participated in exercise before the study. Two of the 3 participants (out of 12) who stopped training also showed functional improvements (Table 4). We had only pretest data available for the participant who dropped out after only 4 weeks and was unavailable for the 6-week test. Compliance was good with the remaining 9 participants. Participants missed from 0 to 3 sessions but finished all 36 sessions.

Figure 1
Usual and fastest gait speed (m/s) in mobility-disabled elders before and after function-focused and gait-speed training. PRE = preintervention.
Table 2
Participant Characteristics
Table 3
Gait, Function, and Strength Results for Mobility-Disabled Participants, M ±SD
Table 4
Gait and Function of Study Dropouts


A 12-week moderate exercise intervention including walk training and functionally focused strength training together with 4 weeks of speed training produced significant improvement in lower extremity strength, as well as improvements in gait and function, in mobility-disabled elders. Gait and functional improvements were maintained at follow-up. A recent study comparing functional-task exercise versus resistance-strength exercise to improve daily function in community-dwelling older women without mobility disabilities demonstrated task-specific results (de Vreede, Samson, van Meeteren, Duursma, & Verhaar, 2005). Daily activity improved more with the functional-task exercise than with the strength training or the control, whereas strength improved more with strength training than in the other two groups. Furthermore, function remained improved 6 months after training stopped in the functional-task group; however, knee-extensor strength had returned to baseline values for the resistance-trained group. Two other studies have used task-specific approaches with more disabled elders (Alexander et al., 2001; Ouslander et al., 2005). Both studies demonstrated improved mobility, ability to stand from a chair, and muscle strength in frail elders. A recent randomized, controlled trial of quadriceps exercise used participants whose mean age was 79 and who demonstrated slowed walking speed or a median, average walking speed of 0.47 m/s (Latham et al., 2003). After an exercise program with ankle weights representing 51% of a 1-RM undertaken three times per week for 10 weeks, no significant increase in quadriceps strength or gait speed occurred compared with an attentional control. Because the first 2 weeks of this study consisted of reduced resistance intensity of 30–40% of 1-RM, this study duration was closer to 8 weeks of training with an adequate intensity. Perhaps the duration was not sufficient, the intensity not adequate, or both (Judge, 2003). These findings, together with our data, suggest the importance of targeted, function-oriented exercise training to improve mobility and function in the elderly.

By combining function-focused strengthening with gait-speed training on a treadmill, we increased usual and fastest gait speed in elders who initially demonstrated gait-velocity impairment. A task-specific aspect of our exercise intervention was the gait speed used during training. Several studies have suggested that high velocity might be an important component of improving muscle strength and power in both highly functioning elders and those who report physical-functional impairments (Bean et al., 2004; Earles, Judge, & Gunnarson, 2001; Fielding et al., 2002). Other studies used exercise machines, and the activities were performed at high velocity (Earles et al.; Fielding et al.). Although these approaches improve muscle strength and power, some investigators have questioned the link between this form of training and improved mobility in elders (Bean et al.; Foldvari et al., 2000). One small pilot study compared weighted vests and functional tasks designed to be specific to mobility-related tasks, with an emphasis on increased velocity of performing the tasks with seated, low-resistance exercises performed three times per week for 12 weeks (Bean et al.). The participants at baseline had physical-performance limitations based on SPPB scores of 7.5 (out of 12), average gait speeds of 0.75 m/s, and five-chair-stand times of 19 s (<11 s is normal). It is interesting that both groups improved function in that their SPPB scores increased and the time for five chair stands decreased. Only the velocity-trained group improved gait speed. Another approach to velocity training for gait is specific speed training on a treadmill (Pohl et al., 2002). This approach involves short bouts of walking on the treadmill with gait speeds increasing from fastest overground walking speed by 10% on each bout so that the speed increases 40–50% by the end of a single training session. Pohl et al. were the first group to report normalized gait speeds after 4 weeks of training three times per week in individuals with stroke who had a walking impairment at baseline. These findings support the idea that speed or velocity training might be important in improving gait function in elders with a gait deficit.

This study had limitations that restrict the generalizability of our findings. The small sample size of community-dwelling, mobility-impaired elders is a distinct limitation. Small samples can produce spurious results by large changes in a few participants or missing adverse events important to the intervention. Although the average weight of the study dropouts was higher than those who completed the study, one of the participants who dropped out (Participant 15) was obese (120 kg). We also did not have a no-intervention control group to compare with the participants who completed the exercise training. A comparison with a control group would provide greater confidence in the outcomes of the intervention. Further studies on a larger population and with a control group design will be necessary to confirm these results. The measures used have excellent psychometric properties that represent a variety of mobility functions and strength characteristics. These measures promise to further describe the relationship between strength and function. We were unable to include all of our participants in the follow-up tests, so further study is needed to define the longer term carryover of our findings. We also had a variable follow-up period because of the availability of the participants. The participants reported that they were walking better and that this enabled them to be more active and to travel. One limitation to supervised exercise programs for elders is that the participants often do not continue the activity after the formal program ends. We selected activities, with the exception of the speed training, that the participants could continue on their own. This might have contributed to the maintenance of improved function at follow-up.


Task-specific intervention can improve function and strength in elders with mobility disability. Speed training might be an important component in improving gait function in this population. Finally, functional status can be retained for 3–6 months after formal training ceases.


This study was supported by the UTMB Claude Pepper Older Americans Independence Center. The exercise intervention took part at the UTMB Alumni Field house. The authors gratefully acknowledge the willingness of the participants who took part in this study.


  • Alexander NB, Galecki AT, Grenier ML, Nyquist LV, Hofmeyer MR, Grunawalkt JC, et al. Task-specific resistance training to improve the ability for activities of daily living–impaired older adults to rise from a bed and from a chair. Journal of the American Geriatrics Society. 2001;49:1418–1427. [PubMed]
  • Bassey EJ, Bendall MJ, Pearson M. Muscle strength in the triceps surae and objectively measured customary walking activity in men and women over 65 years of age. Clinical Science. 1988;74:85–89. [PubMed]
  • Bean JF, Herman S, Kiely DK, Frey IC, Leveille SG, Fielding RA, et al. Increased velocity exercise specific to task (InVest) training: A pilot study exploring effects on leg power, balance, and mobility in community-dwelling older women. Journal of the American Geriatrics Society. 2004;52:799–804. [PubMed]
  • Bendall MJ, Bassey EJ, Pearson MB. Factors affecting walking speed of elderly people. Age and Ageing. 1989;18:327–332. [PubMed]
  • Binder EF, Schechtman KB, Ehsani AA, Steger-May K, Brown M, Sinacore DR, et al. Effects of exercise training on frailty in community-dwelling older adults: Results of a randomized, controlled trial. Journal of the American Geriatrics Society. 2002;50:1921–1928. [PubMed]
  • Bohannon RW. Comfortable and maximum walking speeds of adults 20–79 years. Reference value and determinants. Age and Ageing. 1997;26:15–19. [PubMed]
  • Borg GA. Psychosocial basis of perceived exertion. Medicine and Science in Sports and Exercise. 1982;14:377–387. [PubMed]
  • Brown M, Sinacore D, Host H. The relationship of strength to function in the older adult. Journal of Gerontology. 1995;50A:55–59. [PubMed]
  • Brown M, Sinacore DR, Ehsani AA, Binder EF, Holloszy JO, Kohrt WM. Low-intensity exercise as a modifier of physical frailty in older adults. Archives of Physical Medicine and Rehabilitation. 2000;81:960–965. [PubMed]
  • Chandler J, Duncan RW, Studenski S. Choosing the best measure in frail older persons: Importance of task specificity. Muscle & Nerve. Supplement. 1997;5:S47–S51. [PubMed]
  • Chandler JM, Duncan RW, Kochersberger G, Studenski S. Is lower extremity strength gain associated with improvement in physical performance and disability in frail, community-dwelling elders? Archives of Physical Medicine and Rehabilitation. 1998;79:24–30. [PubMed]
  • Chandler JM, Hadley EC. Exercise to improve physiologic and functional performance in old age. Clinics in Geriatric Medicine. 1996;12:761–784. [PubMed]
  • Cunha I, Henson H, Wankadia S, Protas EJ. Reliability of measures of gait performance and oxygen consumption with stroke survivors. Journal of Rehabilitation Research and Development. 2003;40:19–26. [PubMed]
  • Cunha IT, Henson H, Qureshy H, Williams A, Holmes SA, Protas EJ. Measurement of oxygen consumption emphasizes differences in gait performance among healthy and neurologically impaired individuals. Archives of Physical Medicine and Rehabilitation. 2003;84:1774–1779. [PubMed]
  • Cutlip RG, Mancinelli C, Huber F, DiPasquale J. Evaluation of an instrumented walkway for measurement of the kinematic parameters of gait. Gait & Posture. 2000;12:134–138. [PubMed]
  • Daubney ME, Culham EG. Lower-extremity muscle strength force and balance performance in adults aged 65 years and older. Physical Therapy. 1999;79:1177–1185. [PubMed]
  • de Vreede PL, Samson MM, van Meeteren NLU, Duursma SA, Verhaar HJJ. Functional-task exercise versus resistance strength exercise to improve daily function in older women: A randomized, controlled trial. Journal of the American Geriatrics Society. 2005;53:2–10. [PubMed]
  • Earles DR, Judge JO, Gunnarson OT. Velocity training induces power-specific adaptations in highly functioning older adults. Archives of Physical Medicine and Rehabilitation. 2001;82:872–878. [PubMed]
  • Fiatarone MA, Marks E, Ryan N, Meredith CN, Lipsitz LA, Evans WJ. High-intensity strength training in nonagenarians: Effects on skeletal muscle. Journal of the American Medical Association. 1990;263:3029–3034. [PubMed]
  • Fiatarone MA, O’Neill E, Ryan ND, Clements KM, Solares GR, Nelson ME, et al. Exercise training and nutritional supplementation for physical frailty in very elderly people. The New England Journal of Medicine. 1994;330:1769–1775. [PubMed]
  • Fielding RA, LeBrasseur NK, Cuoco A, Bean J, Mizer K, Fiatarone-Singh MA. High-velocity resistance training increases skeletal muscle peak power in older women. Journal of the American Geriatrics Society. 2002;50:655–662. [PubMed]
  • Foldvari M, Clark M, Laviolette LC, Bernstein MA, Kaliton D, Castadena C, et al. Association of muscle power with functional status in community-dwelling elderly women. The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences. 2000;55:M192–M199. [PubMed]
  • Folstein MF, Folstein SE, McHugh PR. “Mini-Mental State.” A practical method for grading the cognitive status of patients for the clinician. Journal of Psychiatric Research. 1975;12:189–198. [PubMed]
  • Fried LP, Herdman SJ, Kuhn KE, Rubin G, Turano K. Preclinical disability. Hypothesis about the bottom of the iceberg. Journal of Aging and Health. 1991;3:285–300.
  • Guralnik JM, Ferrucci L, Pieper CF, Leveille SG, Markides KS, Ostir GV, et al. Lower extremity function and subsequent disability: Consistency across studies, predictive models, and value of gait speed alone compared with Short Physical Performance Battery. The Journals of Gerontology. Series A, Biological Sciences and Medical Sciences. 2000;55:M221–M231. [PubMed]
  • Guralnik JM, Simonsick EM, Ferrucci L, Glynn RJ, Berkman LF, Blazer DG, et al. A Short Physical Performance Battery assessing lower extremity function: Association with self-reported disability and prediction of mortality and nursing home admission. Journal of Gerontology. 1994;49:M85–M94. [PubMed]
  • Hageman PA, Blanke DJ. Comparison of gait of young women and elderly women. Physical Therapy. 1986;69:1382–1387. [PubMed]
  • Judge JO, Kenny A. Vitamin D and quadriceps exercise—Got milk? Journal of the American Geriatrics Society. 2003;51(3):427–428. [PubMed]
  • Judge JO, Underwood M, Gennosa T. Exercise to improve gait velocity in older persons. Archives of Physical Medicine and Rehabilitation. 1993;74:400–406. [PubMed]
  • Judge JO, Whipple RH, Wolfson LI. Effects of resistive and balance exercises on isokinetic strength of older persons. Journal of the American Geriatrics Society. 1994;42:937–946. [PubMed]
  • Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffee MW. Studies of illness in the aged. Index of ADL: A standardized measure of biological and psychosocial function. Journal of the American Medical Association. 1963;185:914–919. [PubMed]
  • King MB, Whipple RH, Gruman CA, Judge JO, Schmidt JA, Wolfson LI. The performance enhancement project: Improving physical performance in older persons. Archives of Physical Medicine and Rehabilitation. 2002;83:1060–1069. [PubMed]
  • Larish DD, Martin PE, Mungiole M. Characteristic patterns of gait in the healthy old. Annals of the New York Academy of Sciences. 1988;515:18–32. [PubMed]
  • Latham NK, Anderson CS, Lee A, Bennett DA, Moseley A, Cameron ID. A randomized, controlled trial of quadriceps resistance exercise and vitamin D in frail older people: The Frailty Interventions Trial in Elderly Subjects (Fitness) Journal of the American Geriatrics Society. 2003;51:291–299. [PubMed]
  • Lord SR, Lloyd DG, Nirui M, Raymond J, Williams P, Stewart RA. The effect of exercise on gait patterns in older women: A randomized controlled trial. Journal of Gerontology. 1996;51:M64–M70. [PubMed]
  • Lunsford BR, Perry J. The standing heel-rise test for ankle plantar flexion: Criterion for normal. Physical Therapy. 1995;75:694–698. [PubMed]
  • Maki BE. Gait changes in older adults: Predictors of falls or indicator of fear? Journal of the American Geriatrics Society. 1997;45:313–320. [PubMed]
  • McDonough AL, Batavia M, Chen FC, Kwon S, Ziai J. The validity and reliability of the GAITRite system’s measurements: A preliminary evaluation. Archives of Physical Medicine and Rehabilitation. 2001;82:419–425. [PubMed]
  • McMurdo ME, Rennie L. A controlled trial of exercise by residents of old people’s homes. Age and Ageing. 1993;22:11–15. [PubMed]
  • Murphy MA, Olson SL, Protas EJ, Overby AR. Screening for falls in community-dwelling elderly. Journal of Aging and Physical Activity. 2003;11:64–78.
  • Nigg BM, Fisher V, Ronsky JL. Gait characteristics as a function of age and gender. Gait & Posture. 1994;2:213–220.
  • Okuzumi H, Tanaka A, Haishi K, Meguro KI, Yamasaki H, Nakamura T. Age related changes in postural control and locomotion. Perceptual and Motor Skills. 1995;81:991–994. [PubMed]
  • Olson SL, Wang CY, Protas EJ. Risk-intervention strategies for elders: Use of a human performance engineering model to determine patient-specific limitations. Journal of Geriatric Physical Therapy. 2001;24:2.
  • Ouslander JG, Griffiths PC, McConnell E, Riolo L, Kutner M, Schnelle J. Functional incidental training: A randomized, controlled, crossover trial in Veterans Affairs nursing homes. Journal of the American Geriatrics Society. 2005;53:1091–1100. [PubMed]
  • Peloquin L, Gauthier P, Bravo G, Lacombe G, Billiare JS. Reliability and validity of the five-minute walking field test for estimating VO2peak in elderly participants with knee osteoarthritis. Journal of Aging and Physical Activity. 1998;6:36–44.
  • Peterson MGE, Kovar-Toledano JC, Oatis JC, Allegrande JP, McKenzie CR, Gutin B, et al. Effect of a walking program on gait characteristics in patients with osteoarthritis. Arthritis Care and Research. 1993;6:11–16. [PubMed]
  • Pohl M, Mehrholz J, Ritschel C, Ruckriem S. Speed-dependent treadmill training in ambulatory hemiparetic stroke patients. A randomized controlled trial. Stroke. 2002;33:553–558. [PubMed]
  • Price LG, Hewett HJ, Kay DR, Minor MM. Five minute walking test of aerobic fitness for people with arthritis. Arthritis Care and Research. 1988;1:33–37.
  • Protas EJ. Cardiovascular and pulmonary function. In: Van Deusen BD, Brunt D, editors. Assessment in occupational and physical therapy. Philadelphia: W.B. Saunders; 1997.
  • Protas EJ, Holmes SA, Qureshy H, Johnson A, Lee D, Sherwood AM. Supported treadmill ambulation training after spinal cord injury: A pilot study. Archives of Physical Medicine and Rehabilitation. 2001;82:825–831. [PubMed]
  • Rantanen T, Era P, Heikkinen E. Maximal isometric strength and mobility among 75-year-old men and women. Age and Ageing. 1994;23:132–137. [PubMed]
  • Rantanen T, Guralnik JM, Izmirlian G, Williamson JD, Simonsick EM, Ferrucci L, et al. Association of muscle strength with maximum walking speed in disabled older women. American Journal of Physical Medicine & Rehabilitation. 1998;77:299–305. [PubMed]
  • Rubenstein LZ, Josephson AS. The value of assessing falls in an elderly population: A randomized clinical trial. Annals of Internal Medicine. 1990;113:308–316. [PubMed]
  • Sauvage LR, Myklebust BM, Crow-Pan J, Novak S, Millinton P, Hoffman MD, et al. A clinical trial of strengthening and aerobic exercise to improve gait and balance in elderly male nursing home residents. American Journal of Physical Medicine & Rehabilitation. 1992;71:333–342. [PubMed]
  • Stanley RK, Protas EJ. Validity of walking tests to measure exercise performance in elderly women. Physical Therapy. 1991;71:S72–S73.
  • Tinetti ME, Baker DI, McAvay G. A multifactorial intervention to reduce the risk of falling among elderly people living in the community. The New England Journal of Medicine. 1994;331:821–827. [PubMed]
  • Urquhart DM, Morris ME, Iansek R. Gait consistency over a 7-day interval in people with Parkinson’s disease. Archives of Physical Medicine and Rehabilitation. 1999;80:696–701. [PubMed]
  • Wang CY, Olson SL, Protas EJ. Physical-performance tests to evaluate mobility disability in community-dwelling elders. Journal of Aging and Physical Activity. 2005;13:184–197. [PubMed]