Myogenic regulatory factor response to resistance exercise volume in skeletal muscle.

This study examined the impact of resistance exercise volume on myoD and myogenin in rodent quadriceps muscle. Six-month-old male Sprague-Dawley rats (316 +/- 2 g) performed either low-volume (LV; 10 sets x 10 contractions) or high-volume (HV; 20 sets x 10 contractions) resistance exercise at 75% one-repetition maximum. Muscles were analyzed for myogenin and myoD mRNA and protein expression 6, 12, 24 and 48 h post-exercise.

Temporal response of desmin and dystrophin proteins to progressive resistance exercise in human skeletal muscle.

We have investigated the adaptations of the cytoskeletal proteins desmin and dystrophin in relationship to known muscular adaptations of resistance exercise. We measured desmin, dystrophin, and actin protein contents, myosin heavy chain (MHC) isoform distribution, muscle strength, and muscle cross-sectional area (CSA) during 8 wk of progressive resistance training or after a single bout of unaccustomed resistance exercise. Muscle biopsies were taken from the vastus lateralis of 12 untrained men.

Inadequate carbohydrate intake following prolonged exercise does not increase muscle soreness after 15 minutes of downhill running.

In Delayed Onset Muscle Soreness (DOMS), muscles become sore 24 to 48 hours after eccentric and unaccustomed activity. Fiber stiffness, due to decreased muscle glycogen, may predispose muscle to greater damage during eccentric exercise. This study sought to determine if inadequate carbohydrate intake following a protocol to decrease muscle glycogen would increase DOMS after 15 min of downhill running.

Effects of L-tyrosine and carbohydrate ingestion on endurance exercise performance.

To test the effects of tyrosine ingestion with or without carbohydrate supplementation on endurance performance, nine competitive cyclists cycled at 70% peak oxygen uptake for 90 min under four different feeding conditions followed immediately by a time trial. At 30-min intervals, beginning 60 min before exercise, each subject consumed either 5 ml/kg body wt of water sweetened with aspartame [placebo (Pla)], polydextrose (70 g/l) (CHO), L-tyrosine (25 mg/kg body wt) (Tyr), or polydextrose (70 g/l) and L-tyrosine (25 mg/kg body wt) (CHO+Tyr). The experimental trials were given in random order and were carried out by using a counterbalanced double-blind design.

Physiological Effects of Power Volleyball.

In brief The six collegiate male volleyball players in this study had moderate aerobic capacity (56 ml·kg·min) and predominantly fast twitch fiber distribution (57%) in the vastus lateralis muscle. Prolonged volleyball play resulted in a greater depletion of glycogen in slow twitch fibers than in fast twitch and no hint of anaerobic fatigue. These results suggest that in spite of the apparent explosive activity of volleyball, the overall intensity is probably mild to moderate and therefore aerobic endurance may be critical to performance.