This investigation examined the anabolic-hormone response to carbohydrate (CHO) supplementation at rest and after resistance exercise. Nine recreationally trained men randomly underwent 4 testing conditions: rest with placebo (RPL), rest with CHO (RCHO), resistance exercise with placebo (EPL), and resistance exercise with CHO (ECHO). The resistance-exercise protocol was four sets of Smith machine squats with a 10-repetition-maximum load, with 90-s rests between sets. Participants then consumed either a placebo or CHO (24% CHO, 1.5 g/kg) drink. Blood was taken before exercise (Pre), immediately after testing (Post), and then 15 (15P), 30 (30P), and 60 (60P) min after drink ingestion. Blood was analyzed for cortisol, glucose, insulin, and total testosterone (TTST). Cortisol did not change significantly in any condition. Glucose concentrations increased significantly from Pre to 15P and 30P during RCHO and Pre to 15P, 30P, and 60P in ECHO (p ≤&.05). Insulin concentrations increased significantly from Pre to 15P, 30P, and 60P in the RCHO and ECHO conditions (p ≤&.05). There were no significant changes in TTST concentrations during RPL or RCHO. Both EPL and ECHO demonstrated a significant elevation in TTST concentrations from Pre to Post (p ≤&.05). During ECHO, TTST concentrations at 60P were significantly lower than Pre levels (p ≤&.05), but there were no significant treatment differences in TTST concentrations at any time point during the EPL and ECHO conditions. Ingesting CHO after resistance exercise resulted in decreased TTST concentrations during recovery, although the mechanism is unclear.
Sean R. Schumm, N. Travis Triplett, Jeffrey M. McBride and Charles L. Dumke
James L. Nuzzo, Michael J. Cavill, N. Travis Triplett and Jeffrey M. McBride
The primary purpose of this investigation was to provide a descriptive analysis of lower-body strength and vertical jump performance in overweight male (n = 8) and female (n = 13) adolescents. Maximal strength was tested in the leg press and isometric squat. Kinetic and kinematic variables were assessed in vertical jumps at various loads. When compared with females, males demonstrated significantly greater (p ≤ .05) absolute maximal strength in the leg press. However, when maximal strength was expressed relative to body mass, no significant difference was observed. There were no significant differences between males and females in vertical jump performance at body mass.
John Quindry, Lindsey Miller, Graham McGinnis, Megan Irwin, Charles Dumke, Meir Magal, N. Travis Triplett, Jeffrey McBride and Zea Urbiztondo
Acute strength exercise elicits a transient oxidative stress, but the factors underlying the magnitude of this response remain unknown. The purpose of this investigation was to determine whether muscle-fiber type relates to the magnitude of blood oxidative stress after eccentric muscle activity. Eleven college-age men performed 3 sets of 50 eccentric knee-extensions. Blood samples taken pre-, post-, and 24, 48, 72, and 96 hr postexercise were assayed for comparison of muscle damage and oxidative-stress biomarkers including protein carbonyls (PCs). Vastus lateralis muscle biopsies were assayed for relative percentage of slow- and fast-twitch muscle fibers. There was a mixed fiber composition (Type I = 39.6% ± 4.5%, Type IIa = 35.7% ± 3.5%, Type IIx = 24.8% ± 3.8%; p = .366). PCs were elevated 24, 48, and 72 hr (p = .032) postexercise, with a peak response of 126% (p = .012) above baseline, whereas other oxidative-stress biomarkers were unchanged. There are correlations between Type II muscle-fiber type and postexercise PC. Further study is needed to understand the mechanisms responsible for the observed fast-twitch muscle-fiber oxidative-stress relationship.