THE EFFECTS OF ULTRA-FILTERED MILK CONSUMPTION ON STRENGTH AND PERFORMANCE FOLLOWING RESISTANCE TRAINING IN FEMALE COLLEGIATE ATHLETES

Resistance training is beneficial in the improvement of skeletal muscle functionality. Improvements in performance, increased resistance to injury, and great force production are associated with resistance training. Hypertrophy of skeletal muscle mass is important for improving fitness, decreasing body fat percentage, improvements in whole-body metabolism, and enhancements in quality of life. The ability to recovery properly following subsequent training sessions is critical for maximizing training adaptations. Nutrient supplementation has been previously studied. The supplementation of carbohydrates has been shown to replenish muscle glycogen stores. The consumption of carbohydrates following resistance training benefits muscle protein balance by attenuating muscle protein breakdown. Another commonly consumed supplement is amino acids/protein. Supplementation of protein has demonstrated improvements in body composition (i.e. increased fat free mass), increases in hypertrophy, and muscular strength. Two type of proteins used by individuals that resistance train are whey protein and casein protein. Whey protein is a fast digesting protein that leads to quick stimulation of protein synthesis. Casein protein is a slower digesting protein that also attenuates the breakdown of muscle protein. Milk is a natural product that contains carbohydrates, whey protein, and casein protein. Whole milk, low fat milk (i.e., 1-2%), and fat free milk have shown positive results in the ability to improve muscle protein synthesis, lean body mass, strength gains. Therefore, the purpose of the following dissertation is to compare the effects of higher protein, less sugar content chocolate milk to traditional low fat chocolate milk on adaptations to (1) strength and performance measures and (2) body composition following resistance training

The Effects of Ultra-Filtered Milk Consumption on Strength and Performance Following Resistance Training in Female Collegiate Athletes

Resistance training is beneficial in the improvement of skeletal muscle functionality. Improvements in performance, increased resistance to injury, and great force production are associated with resistance training. Hypertrophy of skeletal muscle mass is important for improving fitness, decreasing body fat percentage, improvements in whole-body metabolism, and enhancements in quality of life. The ability to recovery properly following subsequent training sessions is critical for maximizing training adaptations. Nutrient supplementation has been previously studied. The supplementation of carbohydrates has been shown to replenish muscle glycogen stores. The consumption of carbohydrates following resistance training benefits muscle protein balance by attenuating muscle protein breakdown. Another commonly consumed supplement is amino acids/protein. Supplementation of protein has demonstrated improvements in body composition (i.e. increased fat free mass), increases in hypertrophy, and muscular strength. Two type of proteins used by individuals that resistance train are whey protein and casein protein. Whey protein is a fast digesting protein that leads to quick stimulation of protein synthesis. Casein protein is a slower digesting protein that also attenuates the breakdown of muscle protein. Milk is a natural product that contains carbohydrates, whey protein, and casein protein. Whole milk, low fat milk (i.e., 1-2%), and fat free milk have shown positive results in the ability to improve muscle protein synthesis, lean body mass, strength gains. Therefore, the purpose of the following dissertation is to compare the effects of higher protein, less sugar content chocolate milk to traditional low fat chocolate milk on adaptations to (1) strength and performance measures and (2) body composition following resistance training

Évaluation de la capacité fonctionnelle chez des patients atteints de la dystrophie myotonique de type 1

L’évaluation chez les patients atteints de dystrophie myotonique de type 1 (DM1) pose souvent un problème aux cliniciens, car il existe peu d’outils d’évaluation qui permettent d’évaluer objectivement et quantitativement les limitations fonctionnelles. Le but de cette recherche est donc de valider la batterie de tests UQAM-YMCA chez des patients atteints de DM1. Quarante participants (18 hommes et 22 femmes) âgés de 45,9 ±10,8 ans ont réalisé 17 tests regroupés en six déterminants de la capacité fonctionnelle : la vitesse segmentaire, le temps de réaction simple; la force et la puissance musculaire; l’équilibre statique; la mobilité musculoarticulaire; la capacité de déplacement pédestre. Des 40 participants, 20 sont atteints de DM1 et 20 sont sains. La fidélité des tests pour le groupe DM1 a été démontrée par une procédure test-retest réalisée à une semaine d’intervalle et révèle des valeurs de corrélation généralement supérieure à 0,80. En comparant les moyennes du groupe expérimental et du groupe témoin (test-t, échantillons indépendants), on remarque une différence significative (p<0,05) pour 15 des 17 tests. De plus, une analyse discriminante pas-à-pas a permis de classer correctement 97.5 % des participants dans le bon groupe (DM1 vs sains). Globalement, les performances fonctionnelles des personnes atteintes de DM1 sont équivalentes à celles d’individus de plus de 70 ans. La batterie de tests UQAM-YMCA s’avère donc être un outil d’évaluation sensible, précis, valide et fidèle afin d’évaluer la capacité fonctionnelle chez des patients atteints par la DM1

Évaluation de la capacité fonctionnelle chez des patients atteints de la dystrophie myotonique de type 1

L’évaluation chez les patients atteints de dystrophie myotonique de type 1 (DM1) pose souvent un problème aux cliniciens, car il existe peu d’outils d’évaluation qui permettent d’évaluer objectivement et quantitativement les limitations fonctionnelles. Le but de cette recherche est donc de valider la batterie de tests UQAM-YMCA chez des patients atteints de DM1. Quarante participants (18 hommes et 22 femmes) âgés de 45,9 ±10,8 ans ont réalisé 17 tests regroupés en six déterminants de la capacité fonctionnelle : la vitesse segmentaire, le temps de réaction simple; la force et la puissance musculaire; l’équilibre statique; la mobilité musculoarticulaire; la capacité de déplacement pédestre. Des 40 participants, 20 sont atteints de DM1 et 20 sont sains. La fidélité des tests pour le groupe DM1 a été démontrée par une procédure test-retest réalisée à une semaine d’intervalle et révèle des valeurs de corrélation généralement supérieure à 0,80. En comparant les moyennes du groupe expérimental et du groupe témoin (test-t, échantillons indépendants), on remarque une différence significative (p<0,05) pour 15 des 17 tests. De plus, une analyse discriminante pas-à-pas a permis de classer correctement 97.5 % des participants dans le bon groupe (DM1 vs sains). Globalement, les performances fonctionnelles des personnes atteintes de DM1 sont équivalentes à celles d’individus de plus de 70 ans. La batterie de tests UQAM-YMCA s’avère donc être un outil d’évaluation sensible, précis, valide et fidèle afin d’évaluer la capacité fonctionnelle chez des patients atteints par la DM1

Failure and non-failure resistance exercise in trained individuals

The rate and magnitude of muscular strength and power improvements are reduced the longer an individual is engaged in consistent moderate to high intensity resistance exercise training. It is therefore thought that trained individuals need to ‘work harder’ by performing resistance exercise to failure to evoke a large increase in acute fatigue and optimise improvements in muscular strength and power following a period of training. Previous literature has demonstrated that performing resistance exercise to failure stimulates significant acute reductions and chronic improvements in muscular strength and power. However, it is not well understood whether a less stressful and potentially safer exercise modality, such as not completing exercise to the point of failure, can achieve similar or superior outcomes in trained individuals. Disagreement within the current literature that has compared failure and non-failure based resistance exercise prescription may stem from many factors, potentially related to differences in methodological design and a relatively poor understanding of the mechanisms that promote acute and chronic changes in muscular strength and power in trained individuals. Therefore, this thesis contains a series of investigations designed to address the disagreement within the present body of literature and examine gaps in the understanding of the need for trained individuals to perform resistance exercise to failure to improve muscular strength and power. Study 1 investigated changes in muscular strength and power following an acute bout of isometric failure and non-failure based exercise of the knee extensors. Failure exercise was observed to promote greater reductions in muscular strength than a similar bout of non-failure exercise. Peripheral, rather than central mechanisms were found to facilitate reductions in muscular strength with both exercise modalities and likely mediated the greater reduction in muscular strength following failure exercise prescription. As isotonic contractions are more commonly performed in many real world training and competitive environments, Study 2 examined a single session of dynamic failure and non-failure exercise. This investigation demonstrated that a single bout of failure exercise was no more effective at stimulating reductions in plantar flexor strength than a similar bout of non-failure exercise. The decline in strength likely resulted from significant impairment of central neural drive to the muscle. However, a potentiation of muscular excitation-contraction coupling processes seems to have produced an acute increase in muscular power output. The final investigation presented in this thesis (Study 3) examined changes in muscular strength and power following short term failure and non-failure training. Whilst plantar flexor power did not improve with training, failure and non-failure exercise modalities were equally effective at improving plantar flexor strength. The results demonstrated that improvements in muscular strength were likely produced from improved functionality of the muscular contractile apparatus and not from adaptations within spinal or supraspinal neural pathways. The body of work presented in this thesis has demonstrated that both failure and non-failure based exercise evoke an increase in muscular fatigue acutely, which for the most part, was observed to promote a similar acute reduction in muscular strength between modalities. The acute increase in muscular fatigue likely facilitated the similar improvements in muscular strength observed with failure and non-failure exercise following short term training in trained populations. However, the central and peripheral fatigue mechanisms that mediated acute reductions in muscular strength following failure and non-failure exercise did not appear to have any relevance for predicting the training outcome

An examination of agonist and antagonist motor unit firing properties

The interactions between opposing muscle (i.e. agonist and antagonist) groups can be extremely complex, task-dependent, and are still poorly understood. To identify possible origins of the coordination between antagonistic muscle groups, the common or shared sources of neural input need to be understood. The assessment and manipulation of motor unit firing properties, such as synchronization, can provide information regarding the common inputs to opposing muscles. PURPOSE: The purpose of this study was to introduce various interventions to systematically manipulate both agonist and antagonist motor unit firing properties, and obtain a better understanding of the interactions between the two. METHODS: Muscle activity was detected from the biceps brachii ("agonist") and the triceps brachii ("antagonist") during isometric forearm flexions. The signals from these muscles were decomposed into individual motor unit action potential trains. Subsequently, various firing properties such as mean firing rate, recruitment threshold, and synchronization were calculated. On two separate visits, either the agonist or antagonist muscle was fatigued. During another two visits, either the agonist or antagonist muscle underwent 18 minutes of prolonged stretching, which has been shown to significantly desensitize proprioceptors. RESULTS: During co-activation, the antagonist demonstrated significant motor unit synchronization, but to a lesser extent when compared to the agonist. The antagonist also exhibited a substantially smaller recruitment threshold range and higher average firing rates. Fatigue of the agonist did not show any changes to antagonist motor unit firing properties, despite a significant increase in co-activation. Fatigue of the antagonists produced effects on the motor unit behavior of the agonist, such as decreased motor unit synchronization. It was suggested that group III and IV muscle afferents originating from the antagonist were responsible for the change to the agonist. The stretching interventions provided some mixed results, often providing non-uniform changes across motor unit types. For example, agonist low-threshold motor unit pairs demonstrated an increase in short-term synchronization after agonist stretching, but the high-threshold motor unit pairs exhibited a decrease in synchronization. Future studies to help answer follow-up questions were suggested