Abstract
Objectives
To determine the interest of a muscle rehabilitation program following anterior cruciate ligament reconstruction (ligamentoplasty) and the influence of leucine supplementation on the muscle strength of athletes undergoing reathletization.
Material and methods
The authors have analyzed prospectively, in double blind, two groups of athletes (22 versus 23) who had randomly received either leucine supplementation or a placebo. Muscle strength was measured at the beginning and the end of the program In terms of thigh perimeter, isokinetic testing results, single-leg test and percentage of body fat. The reathletization program was identical in the two groups for an average of 2.7 weeks.
Results
By the end of the program, both groups had increased their thigh perimeter at 10 and 15 cm from the patella (respectively 1.2 cm and 1.3 cm, P < 0.0001). Fat mass had decreased by 1.28% ( P = 0.017). Values of isokinetic muscle strength for the injured limb improved by 13 to 55% with highly significant differences. The leucine group generally showed more improved muscle parameters than the placebo group, with only one significant positive result with regard to thigh muscle perimeter at 10 cm from the patella ( P = 0.009).
Conclusion
With or without leucine, the rehabilitation program leads to improved muscle quality. Taking leucine appears to promote muscle recovery of the injured limb with regard to a single parameter (thigh muscle perimeter at 10 cm from the patella), while the other parameters showed no significant improvement. A complementary study associating the recovery phase with other dietary supplements might help to optimize these preliminary results.
Résumé
Objectifs
Préciser l’intérêt d’un programme de renforcement musculaire à distance d’une ligamentoplastie de genou et déterminer l’influence de la supplémentation en leucine sur les capacités musculaires du sportif pendant cette phase de réathlétisation.
Sujets et méthode
Les auteurs ont analysé de façon prospective, en double insu, deux groupes de sportifs (22 versus 23) ayant reçu de façon randomisée, soit une supplémentation en leucine, soit un placebo. Les capacités musculaires ont été mesurées au début et en fin de programme : périmètre des cuisses, tests isocinétiques, triple saut monopodal et pourcentage de masse grasse. Le programme de réathlétisation était identique dans les deux groupes avec une durée moyenne de 2,7 semaines.
Résultats
Grâce au programme, les deux groupes ont amélioré le périmètre de cuisse à 10 et 15 cm de la rotule (respectivement 1,2 cm et 1,3 cm avec p < 0,0001). La masse grasse a diminué de 1,3 % ( p = 0,017). Les valeurs de force musculaire isocinétique du membre lésé se sont améliorées de 13 à 55 % avec des différences très significatives. Le groupe leucine a globalement eu tendance à améliorer ses paramètres musculaires de façon plus importante que le groupe placebo, avec seulement un résultat significatif sur le progrès du périmètre de cuisse à 10 cm de la rotule ( p = 0,009).
Conclusion
Le programme de rééducation (avec ou sans leucine) permet une amélioration des qualités musculaires. La prise de leucine a favorisé la récupération musculaire du membre lésé sur le périmètre de cuisse à 10 cm de la rotule seulement. Les autres paramètres n’ont pas été améliorés significativement. Une étude complémentaire avec d’autres compléments alimentaires ingérés juste après l’effort sur six semaines intégrant une phase de récupération serait intéressante pour optimiser ces résultats préliminaires.
1
English version
1.1
Introduction
Following anterior cruciate ligament reconstruction (ligamentoplasty), the deficit in isokinetic muscle strength on the quadriceps ranges according to the different studies from 23 to 40% at 6 months and from 15 to 20% at 12 months after the intervention . Palmieri et al. and Roewer et al. have demonstrated the impact of maximized quadriceps strength on functional recovery. In this respect, Yüksel et al. has confirmed the interest of reducing the preoperative time interval subsequent to the accident so as to accelerate muscle recovery. And while Laboute et al. have underscored the importance of a muscle strengthening program with regard to both quality of recovery and rapidity of return to sport, few studies have provided precise information on increased muscular capacities after a 2-to-3-week reathletization program.
Moreover, even though some studies have analyzed the interest of amino acid supplementation in athletes, particularly with regard to leucine , no similar work on injured athletes appears to exist. However, leucine assumes a decisive role in muscle synthesis , especially as concerns mRNA translation . leucine would appear to affect protein metabolism by diminishing the rate of degradation and by augmenting protein synthesis. Present in food, leucine is by no means a doping substance; in point of fact, it is an amino acid at once essential and necessary in protein synthesis, and its exogenous intake can consequently be justified.
As a result, it would appear worthwhile to highlight the possible positive impact of a reathletization program on muscle strength and to evaluate the repercussion of leucine intake on the different clinical and paraclinical parameters for muscle assessment in athletes going through a phase of muscle strengthening and reathletization subsequent to their surgery.
1.2
Methods
1.2.1
Subjects
Forty-five athletes participated in the study, which included 32 men and 13 women with a mean age of 24 years (ranging from 18 to 45 years). All of them were athletes competing at a high level (21 at the regional, 21 at the national and three at the international level). They practiced a variety of sports with a preponderance of team sports (17 played rugby, 10 soccer, five team handball, four judo, three basketball, two tennis, one climbing, one motocross and one kite surfing).
All of them had suffered from a rupture of the anterior cruciate ligament and had benefited from a surgery designed to reconstruct the ligament. There was no significant difference between the types of surgeries: 20 STG ligamentoplasties and two free patellar tendon grafts for group A, as opposed to 19 STG ligamentoplasties and three free patellar tendon grafts for group B. Nor was there any significant difference with regard to the number of surgeons for the two groups (seven for group A and nine for group B). The study took place well after the surgery, and the athletes were all in the midst of reathletization. There was no significant difference between the two groups as concerns time elapsed since the operation: 190 days (±52) for group A, and 211 days (±55) for group B. All participants had signed an informed consent form, and the study was approved from an ethics standpoint by the French Comité de Protection des Personnes (Sud Ouest et Outre Mer III, reference DC 2012/06).
Were excluded from the study: athletes staying at the center for less than 2 weeks of rehabilitation, osteotomies, chrondoplasties and complex associated ligament injuries. In addition, the athletes selected to participate were not undergoing any medical treatment.
1.2.2
Protocol
1.2.2.1
The clinical trial
We analyzed prospectively, in double blind, two groups of athletes who had randomly received either leucine supplementation or a placebo. An intervener exterior to the study had determined the constitution along with the randomization of the patient groups; only the intervener knew which group had received leucine, and which group had received the placebo. On the other hand, the intervener assumed no role in either product distribution or data collection and analysis. Interpretation and inter-group comparison were carried out by an examiner different from the one distributing the products and collecting the data. Composition of the groups was revealed only when the final draft of the study was being prepared, subsequent to completion of the various statistical calculations. Group A was known as the leucine group, and group B was placebo.
1.2.2.2
The rehabilitation protocol
During the “reathletization”-type rehabilitation program, which lasted 2 to 3 weeks (2.7 weeks ± 0.7 for group A, and 2.7 weeks ± 0.4 for group B), the patients benefited from daily muscle strengthening exercises, proprioception and running. In physiotherapy, the treatment consisted in massages, stretching, electrostimulation, proprioception, closed kinetic chain (CKC) exercises on a stepper and press, as well as both concentric and eccentric open kinetic chain (OKC) exercises. The eccentric isokinetic exercises were performed daily at varying speeds according to the STANISH protocol at 30, then 50 and finally 70% of maximal eccentric force. As concerns physical preparation, its management associated cardiovascular or aerobic exercise on an ergometric stationary bicycle with aquatraining, upper body muscle building and circuit training in an athletization zone. The different exercises were precisely codified and applied to each and every one of the patients, all of whom went through a similar program in terms of contents, types of exercise and overall workloads .
1.2.2.3
The supplementation protocol
The leucine and the placebo were distributed in the form of tablets of the same appearance, size and color, with a dose of 330 mg of leucine by capsule. The leucine is L. leucine. The coating agent was composed of a gelatin emulsifying agent: microcrystalline cellulose. The energy value of 4 leucine capsules consisted in: 1.5 g proteins (including 1.2 g leucine ), 0.12 g carbohydrates, 0.01 g lipids, which means 6.59 kcal/25.54 kJ. Throughout their rehabilitation program, they received 1 tablet in the morning and at noontime, and two in the evening. Moreover, a dietician used the results of a questionnaire to calculate each athlete’s daily nutritional intake in terms of proteins (g/kg/day), which averaged out at 1.3 g/kg/day in the two groups, with the extremes ranging from 0.75 to 2.02 g/kg/day. Since the athletes all used the same menus throughout the program, dietary leucine intake was equivalent in the two groups.
1.2.3
Material and measurements
1.2.3.1
Thigh perimeter
Thigh perimeter was measured by experienced clinicians with a tape measure at 10 cm and 15 cm from the top of the patella of each limb. The difference in the values thereby recorded before and after the rehabilitation program was calculated.
1.2.3.2
The isokinetic tests
Muscle strength measurements were carried out by means of an isokinetic apparatus (Biodex) at speeds of 90°/s and 240°/s concentrically and eccentrically following warm-up. The patient remained in a seated position, with his or her hands on the handles. Range of motion for the knee was limited to 0–90°. A weight correction was carried out. The number of repetitions ranged from 5 to 15 according to speed. Peak force was the parameter analyzed (in Newtons). The difference between the healthy side and the injured side was calculated according to the formula (1−[peak force injured side/peak force healthy side]) × 100.
1.2.3.3
The single-leg (hopping) long jump
Three maximal long jumps on the healthy limb and on the injured limb were performed turn by turn. The first jump began with the healthy limb. After each jump, the patient returned to the starting line, changed sides (or legs) and carried out another trial. The figures recorded for each limb were measured in centimeters. The mean figure was then calculated for the three jumps with the healthy limb and the three jumps with the injured limb. Expressed in percentage, the mean difference in jump length between the healthy side and the injured side provides simple quantification of the strength deficit on the injured side.
1.2.3.4
Body fat
In order to calculate body fat, we employed a method allowing for measurement of cutaneous folds with a Harpenden skin fold caliper. All of the measurements were carried out by a single experienced professional. Four different measurements were taken: bicipital fold (vertical, located midway between the high and low biceps insertion), subscapular fold (diagonal downwards and outwards, on the posterior side of the scapula) tricipital fold (vertical on the posterior side of the triceps) and umbilical fold (vertical, located 2 cm to the right of the umbilicus). The data were then transferred to a Durnin table (sum total of the four cutaneous folds) so as to calculate the percentage of body fat.
1.2.4
Statistical analysis
We used the Chi 2 test in order to underscore the statistical differences between the qualitative variables. We tested the normality of the distribution of the quantitative variables by the Shapiro-Wilk test, and then compared the quantitative variables with a Student’s t test. We had preliminarily verified the homoscedasticity hypothesis and used Fisher’s exact test when comparing small samples. We opted for the Student’s t test on paired data so as to compare the values for each group at the beginning and the end of the program. The calculations were performed on Graph-Pad PRISM (registered trademark) 2007 version 5.00 and R working environment version 2.9.0. The results were verified by a statistician. The significance threshold was set at P < 0.05. The values included in the tables represent the mean ± the standard deviation. The items not mentioned in the files were not taken into account in the statistical calculations, but their number was indicated.
1.3
Results
1.3.1
Population characteristics
Groups A and B were composed respectively of 22 and 23 athletes ( Table 1 ). The characteristics of each group were similar in terms of sex, age, level, sports practiced and morphotype elements such as size, weight and body mass index (BMI).
| Age (years) | Sex | Height (cm) | Weight (kg) | BMI | Sports | Level | |
|---|---|---|---|---|---|---|---|
| Group A | 23.8 ± 5.6 | 14 M, 8 W | 176.8 ± 10.7 | 78.3 ± 15.9 | 25 ± 3.3 | 6 rugby, 4 soccer, 4 handball, 3 basketball 5 other | 11 R, 8 N, 3 I |
| Group B | 24.8 ± 5.8 | 19 M, 4 W | 179 ± 9.5 | 81.8 ± 15.8 | 25.6 ± 2.9 | 11 rugby, 5 soccer, 1 handball, 1 volleyball 5 other | 11 R, 12 N |
1.3.2
Evolution of the parameters in all the population measuring the effect of the rehabilitation program
Thigh perimeters at 10 and 15 cm from the patella significantly increased ( P < 0.0001) on the injured side ( Tables 2 and 3 ). Isokinetic muscle strength increased according to the speeds being tested (six modes of analysis) with highly significant differences on the injured side ( P = 0.0006 at 0.001). The single-leg long jump showed no improvement during the program. Body fat significantly decreased ( P = 0.01).
| Evolution in cm of thigh perimeter at 10 cm | Evolution in cm of thigh perimeter at 15 cm | Evolution in % of single-leg long jump | Evolution in % of body fat | |
|---|---|---|---|---|
| Injured side (mean) | +1.2 ± 1.4 | +1.3 ± 1.6 | −1.3 ± 18 | −1.3 ± 3.4 |
| P | < 0.0001 | < 0.0001 | NS | 0.017 |
| Quadriceps (concentric at 90°/s) | Quadriceps (concentric at 240°/s) | Quadriceps (excentric) ( n = 13) | Hamstring (concentric at 90°/s) | Hamstring (concentric at 240°/s) | Hamstring (excentric) ( n = 13) | |
|---|---|---|---|---|---|---|
| Injured side (% mean) | +20 ± 20.9 | +21.3 ± 22.8 | +55 ± 44 | +13.9 ± 21.6 | +16.6 ± 20.5 | +30 ± 62 |
| P | 0.007 | 0.002 | 0.0009 | 0.0007 | 0.0007 | 0.001 |
1.3.3
Comparison of the two groups with the different parameters
1.3.3.1
Thigh perimeter
At the beginning of the program, there existed no significant difference between the two groups ( Table 4 ). At 10 cm from the patella, the perimeter of the injured side had undergone greater increase in group A than in group B, and the difference was significant ( P = 0.009). At 15 cm from the patella the increased perimeter on the injured side was not significantly different ( P = 0.38).
| Evolution of thigh perimeter at 10 cm from the injured side (in cm) | Evolution of thigh perimeter at 15 cm from the injured side (in cm) | |
|---|---|---|
| Group A | +1.7 ± 1.3 | +1.6 ± 0.9 |
| Group B | +0.69 ± 1.2 | +1.16±1 |
| P | 0.009 | 0.38 |
1.3.3.2
The isokinetic tests
At the beginning of the program, there existed no significant difference between the two groups. Even though the difference was non-significant, muscle strength had a tendency ( P = 0.07 for the quadriceps concentrically mode at slow speed, and P = 0.1 eccentrically) to increase more pronouncedly in group A ( Table 5 ). At the end of the program, the muscle strength deficit of the eccentric quadriceps ( Table 6 ) had a tendency to increase more markedly in group A than in group B, but without significant difference ( P = 0.05).
| Quadriceps (concentric at 90°/s) | Quadriceps (concentric at 240°/s) | Quadriceps (excentric) | Hamstring (concentric at 90°/s) | Hamstring (concentric at 240°/s) | Hamstring (excentric) | |
|---|---|---|---|---|---|---|
| Group A | +26 ± 19 | +18.9 ± 17 | +68.3 ± 54, n = 7 | +18.9 ± 17 | +22.3 ± 16 | +60 ± 55, n = 7 |
| Group B | +9 ± 20 | +22% ± 27 | +23.2 ± 19, n = 6 | +18.7 ± 25 | +22.1 ± 24 | +24.8 ± 19, n = 6 |
| P | 0.07 | NS | 0.1 | NS | NS | NS |
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