par Nutrimuscle-Conseils » 30 Sep 2024 17:05
Effects of whey protein on body composition, biochemical profile, and high intensity physical performances in well-trained endurance runners
Effets des protéines du lactosérum sur la composition corporelle, le profil biochimique et les performances physiques de haute intensité chez les coureurs d’endurance bien entraînés
Science & Sports Volume 39, Issue 7 , October 2024, Pages 588-598 M.B. Mhamed
Objective
To assess the effects of 2-months of 30 g/day whey protein supplementation on body composition, selected biochemical parameters and high intensity physical performance in 29 well-trained endurance athletes.
Materials and methods
Subjects were randomly divided into 2 groups: whey group (n = 20), and control group (n = 9). Body composition, selected biochemical parameters, and Wingate peak power (PP) and mean power (MP), and maximal aerobic speed (MAS) were assessed before and after the intervention in both groups. The two groups continued to follow their specific training regimens during the 2-month intervention.
Results
After this period, body mass was increased in the whey group (3.8%, P < 0.001), with a decrease in percentage body fat (P < 0.004), and an increase in leg muscle volume (P < 0.001). These parameters were unchanged in the control group. Resting values of plasma ASAT, ALAT, CK, total cholesterol, LDL-cholesterol (all at P < 0.05), and urea (P < 0.01) were reduced in the whey group after the intervention. The control group showed no changes. The whey group had increased PP and MP, (P < 0.001 both) and MAS (P < 0.05), and decreased fatigue index (P < 0.05) after the 2-month intervention. The control group showed no significant changes of these measures.
Conclusion
Whey protein supplementation combined with 2-month endurance training leads to a reduction of body fat, and increased leg muscle volume. ASAT, ALAT, and CK, were also reduced. These changes were accompanied by improvements in PP, and MP, as well as MAS in well-trained endurance athletes. These data suggest that protein supplementation could also be recommended for endurance athletes to support recovery and high intensity physical performances.
Résumé
Objectif
Évaluer les effets de 2 mois de supplémentation de 30 g/jour de protéines de lactosérum sur la composition corporelle, des paramètres biochimiques et la performance physique à haute intensité chez des athlètes d’endurance entraînés.
Matériels et méthodes
Les sujets ont été divisés d’une façon aléatoire en 2 groupes : un groupe supplémenté en protéines de lactosérum (n = 20) et un groupe témoin (n = 9). La composition corporelle, des paramètres biochimiques, le pic de puissance Wingate (PP), la puissance moyenne-Wingate (MP) et la vitesse aérobie maximale (MAS) ont été évalués avant et après l’intervention chez les deux groupes. Les deux groupes ont continué à suivre leur programme d’entraînement habituel pendant d’intervention.
Résultats
Après l’intervention, la masse corporelle a augmenté chez le groupe protéines (3,8 %, p < 0,001), avec une diminution du pourcentage de masse grasse (p < 0,004) et une augmentation du volume musculaire des membres inférieurs (p < 0,001). Ces paramètres étaient inchangés chez le groupe témoin. Les valeurs plasmatiques de l’ASAT, de l’ALAT, de la CK de repos, du cholestérol total, du LDL-cholestérol (tous à p < 0,05) et de l’urée (p < 0,01) ont été réduites chez le groupe protéines après l’intervention. Le groupe témoin n’a montré aucun changement. Le groupe protéines avait augmenté la PP et la MP (p < 0,001), l’indice de fatigue (p < 0,05) et la MAS (p < 0,05) après l’intervention. Le groupe témoin a montré une légère amélioration des performances physiques, mais qui n’était pas statistiquement significative.
Conclusion
Une supplémentation en protéines de lactosérum combinée à un entraînement d’endurance de 2 mois a réduit le pourcentage de masse grasse et augmenté le volume musculaire des membres inférieurs. Les valeurs de l’ASAT, ALAT et CK ont été réduites. Ces changements étaient accompagnés d’améliorations de la PP et de la MP-Wingate, ainsi que de la vitesse maximale aérobie chez les athlètes d’endurance. Ces données suggèrent qu’une supplémentation en protéines du lait pourrait être ponctuellement recommandée aux athlètes d’endurance afin de favoriser la récupération et la performance physique intense.
Introduction
Whey protein has been widely used in untrained subjects [1] or in power trained athletes to increase muscle mass and to improve strength and physical performance [2], [3], [4]. However, there are relatively few studies examining the effects of whey protein supplementation on body composition and performance in well-trained endurance athletes [5], [6] and the results are sometimes conflicting. For example, Huang et al. [5] reported increased distance run (from 3742 ± 68 to 3776 ± 58 m) in 12-min running test associated with an increase in whole body muscle mass (32.1 ± 1.6 to 34.3 ± 2.4 kg), with no difference in performance in the placebo group; they also found decreases in “liver” enzymes, LDH, and creatine kinase (muscle damage markers) after 5-weeks of 33.5 g/day whey protein supplementation in endurance track runners. However, Roberson et al. [6] found increased lean mass, a tendency of mitochondrial capacity to be improved, but without significant improvement in physical performance after the ingestion of 25 g whey protein (post-exercise and pre-sleep) during 10 weeks in endurance runners. The inconsistent results of the effects of whey protein supplementation on endurance exercise performance and the associated post-exercise recovery parameters are in part related to some methodological differences such as the duration of supplementation, the amount, type, and timing of protein intake, and the training status of the subject.
According to Phillips and van Loon [7], endurance athletes need more protein than the current recommendation of 0.8 g/kg/day for normal subjects, in order to achieve training adaptations and improve performance [7], [8]. The position statement of the International Society of Sports Nutrition (ISSN) stated that protein supplementation may help to offset muscle damage during and following exercise and promote muscle recovery in athletes [9]. The rationale for the increased protein intake for endurance athletes is that their training volume is typically greater than for powerful athletes, i.e. about 6 days per week so as to attain adequate training distance per week. Furthermore, endurance athletes often use a mixed training approach incorporating eccentric exercises, plyometrics and obstacle courses; these training regimens often induce muscle catabolism as well as resulting in muscle damage [10], [11]. Muscle protein catabolism during exercise is not desirable as the amino acids lost in this process are required to support post-exercise and training adaptations. Also, excessive muscle damage with associated inflammation and requirement for muscle repair slows muscle recovery and impairs subsequent performance [12]. In this context, the recovery process is important for subsequent training sessions and for performance. Therefore, increasing nutrient availability, such as proteins and carbohydrate in the post-training recovery period is important to replenish substrate stores and facilitate repair and muscle protein synthesis [13]. Regarding protein intake, the timing of ingestion is important for muscle protein synthesis. Several studies pointed out the relevance of dietary protein ingestion after exercise, which stimulates muscle protein synthesis, inhibits protein breakdown following resistance as well as endurance type exercise [14], [15].
Because there appears to be controversy surrounding the use of protein supplementation by endurance athletes (type, and amount of protein supplemented per day, duration and timing of supplementation), we were interested in determining if a dose of 30 g/day of whey protein supplementation provided after the training session for 8 weeks may support muscle adaptations related to recovery and high intensity physical performances.
Thus, the objective of the present study was to assess the effect of whey protein supplementation on plasma concentrations of muscle enzymes (ASAT, ALAT, CK), and selected biochemical parameters, body composition, and high intensity physical performances in well-trained endurance athletes. The hypothesis was that endurance training combined with whey protein supplementation provided within 30-min post-training for a 2-month period could reduce plasma concentrations of muscle enzymes, and increase high intensity exercise performance in well-trained endurance athletes.
