Objective: It is unknown whether muscle aponeurosis area is exaggerated in pennate muscle that has undergone extreme hypertrophy as a result of exercise. We compared the morphological characteristics of deep muscle aponeurosis in resistance-trained athletes with those in untrained students. Design: Cross-sectional study. Methods: Eight elite male Olympic weightlifters and 8 male college students volunteered for the study. Magnetic resonance imaging was used to obtain images from the first cervical vertebra to the ankle joint for each subject, and total and thigh skeletal muscle volumes were determined. Deep muscle aponeurosis in the vastus lateralis (VL) muscle was determined by summing the product of the length of the dark black line (aponeurosis) in each MRI slice and the slice thickness. Results: Fat-free mass and total and thigh muscle masses were greater (P<0.01) in the weightlifters than in the students. Aponeurosis length in the VL was similar in both groups, but the maximal width of the VL aponeurosis was greater (P<0.01) in the weightlifters (11.7 cm) than in the students (8.8 cm). Additionally, VL aponeurosis area in the P between quadriceps muscle mass and VL aponeurosis area (r=0.85, P<0.01). Conclusion: Muscle aponeurosis area may be increased by high-intensity resistance training, which is associated with muscle mass accumulation and muscle fiber geometry in hypertrophied muscle.
Objectives: To determine if force differences exist between isometric pulling positions corresponding to key positions of the deadlift. Design: Cross-sectional evaluation of isometric strength Methods: 14 powerlifters performed isometric pulls on a force plate at 3 key positions related to the deadlift (at the floor, just above the patella, and 5-6 cm short of lockout) and in the mid thigh pull position (MTP). A 1x4 repeated measures ANOVA was used to ascertain differences between the various pulling positions tested. Bonferroni-adjusted paired samples t-tests were used post-hoc. Results: Forces generated at each bar height were significantly different (F(3,39) = 51.058, p<0.05, η2=0.80). Paired samples t-tests showed significant differences between positions, revealing a trend of greater force generation at increasing heights for positions corresponding to the deadlift. Force generated in the mid thigh pull position was significantly higher than any other position. Conclusion: In positions corresponding to the deadlift, force generation increases at higher bar heights.
Current recommendations for training protocols aimed at increasing muscle mass are commonly based on a percentage of the concentric one repetition maximum (1RM) for a particular exercise. However, research utilizing lower exercise intensities (20- 30% 1RM) has been observed to result in skeletal muscle hypertrophy similar to that of higher intensity resistance training. These findings appear to question the overall importance of exercise intensity for increasing muscle mass. Objectives: The purpose of this manuscript is to discuss the skeletal muscle hypertrophy exercise intensity recommendations and provide discussion on overall exercise volume, which is likely more important for stimulating skeletal muscle hypertrophy than exercise intensity per se. Design and Methods: Non-systematic review Results: It appears that a large portion of the exercise recommendations for skeletal muscle hypertrophy appear to be based on protocols that elicit short term changes in systemic ‘anabolic' hormones; although little conclusive evidence exists to support that ‘anabolic' hormone hypothesis. Exercise volume may be of much more importance for stimulating and maximizing the duration of the muscle protein synthesis (MPS) response than exercise intensity per se. In addition,chronic training studies confirm the acute findings that volume, not exercise intensity is the mediating factor for skeletal muscle hypertrophy. Conclusion: The data suggests that skeletal muscle hypertrophy recommendations on the basis of exercise intensity are too simplistic and more focus should instead be placed on total exercise volume. The current recommendations for muscle hypertrophy do not reflect current science.
Exercise-induced muscle damage (EIMD) is a well-known phenomenon that happens after performing lengthening contractions or unaccustomed exercise.Many studies have tried to reduce this muscle damage yet muscle damage is also known to produce a protective effect against future damaging exercise bouts. Objectives: The purpose of this paper was to briefly discuss how EIMD can result in negative consequences and examine evidence for or against potential benefits of EIMD. Design and Methods: Non-systematic review Results: EIMD is detrimental in that it produces prolonged decreases in force and decreased exercise performance. If muscle damage is severe it may result in exercise-induced rhabdomyolysis and when it occurs in combination with dehydration or heat stress, it may potentially lead to life threatening issues such as acute kidney failure. Despite its detrimental effects, some have suggested possible benefits from EIMD. The potential benefits of EIMD include the repeated bout effect and muscle hypertrophy but these benefits can be produced without inducing EIMD. Conclusion: After examining the detrimental and beneficial effects of EIMD, it seems that the detrimental effects outweigh any possible benefits of EIMD and many of the proposed benefits (repeated bout effect and hypertrophy) can be produced without EIMD.
Prostaglandins are a diverse group of eicosanoid hormones that modulate various processes, many of which are related to inflammation. Due to this, prostaglandins are the target of cyclooxygenase (COX) inhibitor drugs. Prostaglandin F2α (PGF2α) mediates processes integral to successful skeletal muscle regeneration, roles elucidated through suppression of its production with various COX-inhibitors. Objective: To provide a comprehensive review of literature regarding roles for the COX-metabolite PGF2α in skeletal muscle regeneration and consequences of its suppression with COX-inhibitors. Design: Systematic review. Method: Recognition was given to early in vitro studies that first established roles for PGF2α in two specific regenerative processes, and attention was then directed to human experiments investigating the PGF2α response to aerobic and resistance exercise. Results:PGF2α mediates protein synthesis and satellite cell activity post-injury.Although methodological differences exist between experiments, research has unanimously demonstrated COX-mediated suppression of PGF2α diminishes these regenerative processes. Conclusions:All experiments in humans have been acute exercise interventions. Studies involving repeated exercise and repeated administration of COX-inhibitors seem warranted to determine if chronic use impedes skeletal muscle regeneration after exercise. Such a finding may hold serious implications for recreational athletes, patients, and clinicians managing musculoskeletal pain or diseases with regular use of COX-inhibitors.