Of the 1,674 questionnaires distributed, 412 were returned and 403 were within the age range required. The highest response rate was from WCDP athletes (43%), followed by TASS (29%) and National Government Bodies (NGB) athletes (18%), calculating an overall response rate average of 25%. Overall this average was brought down due to a very low response rate from the football players in the NGB athlete group. The sample predominantly consists of white (93.8%) male (64.5%) athletes compared to females (33.0%) with 2.5% of the information missing. Over two thirds of respondents (67.0%) are between age 16 and 19 whilst the 12–16 and the 20–21 age groups formed 12.5% and 19.9%, respectively. Age information for 0.5% of the participants was missing. The mean age was 17.66 ± 1.99.
Close to one-third of the athletes in the sample were rugby union players (27.8%), followed by football players (13.9%) and swimmers (6.7%). Table tennis, equestrian, fencing, synchronised swimming, rowing, diving, water polo, canoeing, golf, judo, orienteering, taekwondo, tennis, cricket and disability athletics were contributed to the sample by 1 to 5%, listed in decreasing order. The individual contribution from the remaining 17 sports was ≤ 1%. The majority of the young athletes (78.4%) did not believe that nutritional supplementation was necessary to be successful in sport with only 4.2% claiming not having the knowledge to answer the question. However, contrary to this belief, almost half of the respondents (48.1%) reported using at least one supplement from the list provided (Figure ) with a considerable proportion of athletes using more than one supplements. On average, 2.96 supplements were used among the elite young athletes (574 instances with 194 supplement users).
Figure shows the proportion of athletes in the sample and among those who reported supplement use. The most popular supplements were: energy drinks (41.7% of all athletes and 86.6% of supplement users reported), followed by vitamin C (22.8% and 47.4%), multivitamin (22.8% and 47.2%), whey protein (21.3% and 44.3%), creatine (13.4% and 27.84%), echinacea (7.7% and 16.0%), caffeine (5.7% and 11.9%), iron (4.7% and 9.8%), ginseng (1.7% and 3.6%) and melatonin (1.0% and 2.1%). Among other supplements, glutamine/glucosamine, branch-chain amino acid, cod liver oil, B vitamin complex, Maximuscle, Met-RX, norateen, carbohydrates and protein shakes, omega oils and probiotics were listed.
Among the desired outcomes resulting from supplement use, maintaining strength was the most frequently cited reason among all athletes in the sample (34.7%) and supplement users (72.2%), followed by avoiding sickness (56.1% of users) and endurance enhancement (55.2% of users). One-third of the supplement user athletes listed the ability to train longer (30.4%) and helping to recover (32.5%) among the reasons, whereas 23.2% take supplements to remedy imbalanced diet (Figure ).
Overcoming injury and other reasons equally contributed with 16.5% to the picture. Given the age group, an unexpectedly modest proportion (5.7%) reported lack of sleep among the reasons, whereas 13 athletes (6.7%) claimed that they do not know why they take supplements.
With regard to sources of advice on nutritional supplementation, many young athletes appear to decide on their nutritional supplementation themselves without advice. The considerable overlap between self-managed supplementation and medical advice (Figure ) is, however, somewhat reassuring. The coaches' role in advising athletes on supplements, especially in taking energy drinks and protein was also evidenced. Among health professionals, athletes indicated that advice was sought from nutritionists and/or physiotherapists. The only exception to this pattern was iron supplementation, which was taken following general practitioners' advice.
Source of information regarding the supplements reported, expressed as ratio between the number of sources and incidents reported.
To assess athletes' understanding of the benefits of nutritional supplements and to investigate the presence or lack of informed choices, the association between used supplements and reasons for using supplements were tested. Under an assumption that the choices of athletes were informed ones, a strong association is expected between a given reason for their use and a given supplement. The most relatively strong associations fell in the performance quadrant using creatine, whey protein and energy drinks (Tables and ). Notably, the strongest associations were found between maintaining strength and whey protein (χ2 = 94.355, ϕ = .484, p < .001) and creatine (χ2 = 80.327, ϕ = .447, p < .001).
Among health maintenance reasons, only multivitamin showed a considerable congruence with aiding recovery. Interestingly, no association between vitamin C and health maintenance was evidenced.
Table shows the agreement expressed as percentages between rationale and practice. In an ideal situation, assuming that all athletes are fully informed, the Yes-Yes quadrant (i.e. using a substance) should be 100%. A high percentage in the mixed cells (YN and NY) indicates lack of knowledge or potentially random choice of supplements. Compared to this best case scenario, the best agreement between rationale and practice was found for energy drinks and endurance enhancement. 69.2% of the respondents reported using energy drinks when endurance enhancement was listed among the reasons for taking supplements. As for creatine and whey protein, among those who claimed to use supplements to maintain strength, only 34.4% actually reported using creatine and 48.6% used whey protein. Considering that all athletes in the sample were supplement users, these athletes used supplements other than those that would help to achieve their expressly stated outcome (e.g. increased strength).
Figure further investigates the role of various formal and informal support personnel in the use of creatine, protein and energy drinks. As expected, the majority of the supplement user athletes reported the consumption of energy drinks based on their own decisions, although a relatively high proportion of athletes reported that coaches also advised them on these drinks. On the contrary, sponsors' contributions were unexpectedly low. Congruent with the overall picture, general practitioners and team doctors appear to be less influential than physiotherapists, coaches or nutritionists. This result clearly warrants further qualitative research.
Source of advice selected for taking creatine (54), energy drinks (168) and whey protein (86) among supplement user young athletes (n = 194).