The purpose of this trial was to examine the effects of self-selected exercise intensities plus either whey protein or placebo supplementation on vital signs, body composition, bone mineral density, muscle strength, and mobility in older adults. A total of 101 participants aged 55 years and older (males [n = 34] and females [n = 67]) were evaluated before and after 12 weeks of self-selected, free-weight resistance exercise plus 30 min of self-paced walking three times per week. The participants were randomized into two groups: whey protein (n = 46) or placebo (n = 55). Three-way mixed factorial analyses of variance were used to test for mean differences for each variable. The 12 weeks of self-selected, self-paced exercise intensities improved resting heart rate, fat-free mass, percent body fat, handgrip strength, bench press strength, leg press strength, and all mobility measurements (p < .05) in males and females despite supplementation status. This suggests that additional protein in well-fed healthy older adults does not enhance the benefit of exercise.
Ashley A. Herda, Brianna D. McKay, Trent J. Herda, Pablo B. Costa, Jeffrey R. Stout and Joel T. Cramer
Trent J. Herda, Philip M. Gallagher, Jonathan D. Miller, Matthew P. Bubak and Mandy E. Parra
Background: Skeletal muscle is overlooked in the realm of insulin resistance in children who are overweight and obese despite the fact that it accounts for the most glucose disposal. Objectives: Therefore, this study examined fasted glucose levels and muscle cross-sectional area and echo intensity (EI) via ultrasound images of the first dorsal interosseous, vastus lateralis, and rectus femoris in children who are normal weight and overweight and obese aged 8–10 years. Methods: In total, 13 males (age = 9.0 [0.7] y) and 7 females (age = 9.0 [0.8] y) volunteered for this study. Independent samples t tests and effect sizes (ESs) were used to examine potential differences in skeletal muscle composition and glucose concentrations. Results: There were no significant differences between groups for glucose concentration (P = .07, ES = 0.86); however, the children who were overweight and obese had significantly greater EI (P < .01, ES = 0.98–1.63) for the first dorsal interosseous, vastus lateralis, and rectus femoris and lower cross-sectional area when normalized to EI when collapsed across muscles (P < .04, ES = 0.92). Glucose concentrations correlated with EI and cross-sectional area/EI for the vastus lateralis (r = .514 to −.593) and rectus femoris (r = .551 to −.513), but not the first dorsal interosseous. Discussion: There is evidence that adiposity-related pathways leading to insulin resistance and skeletal muscle degradation are active in young children who are overweight and obese.
Pablo B. Costa, Eric D. Ryan, Trent J. Herda, Ashley A. Walter, Katherine M. Hoge and Joel T. Cramer
This study examined the acute effects of passive stretching on electromechanical delay (EMD), peak twitch force (PTF), rate of force development (RFD), and peak-to-peak M-wave (PPM) for the soleus muscle during evoked isometric plantar flexion muscle actions. Fourteen men (mean age ± SD = 21.2 ± 2.4 years; body mass = 80.0 ± 14.9 kg; height = 176.9 ± 7.2 cm) and 20 women (20.9 ± 2.5 years; 61.3 ± 8.9 kg; 165.3 ± 7.5 cm) volunteered for the study. Five single-square, supramaximal transcutaneous electrical stimuli (each separated by 5 s) were delivered to the tibial nerve before and after passive stretching. A time × gender interaction was observed for EMD, and the post hoc dependent-samples t tests indicated that EMD increased 4% for the women (p = .023), but not for the men (p = .191). There were no other stretching-related changes for PTF, RFD, or p-p M-wave for either the men or women (p > .05). These findings tentatively suggested that mechanical factors related to the stiffness of the muscle-tendon unit may contribute to the explanation for why stretching caused an acute increase in the EMD during evoked twitches in the women, but not in the men.
Ashley A. Walter, Abbie E. Smith, Trent J. Herda, Eric D. Ryan, Jordan R. Moon, Joel T. Cramer and Jeffrey R. Stout
The purpose of this study was to examine the effects of 5 d of creatine (Cr) loading on the electromyographic fatigue threshold (EMG FT) in college-age men. Sixteen men (age 22.4 ± 2.6 yr, height 177.4 ± 6.8 cm, weight 79.5 ± 10.6 kg; M ± SD) participated in this double-blind study and were randomly placed into either placebo (Pl; 10 g of flavored fructose powder per packet; n = 8) or Cr (5 g dicreatine citrate plus 10 g of flavored fructose powder per packet; n = 8) loading groups. Each participant ingested 1 packet 4 times/d, totaling 20 g/d for 5 days (loading). Before and after loading, each participant performed a discontinuous cycle-ergometer test to determine his EMG FT, using bipolar surface electrodes placed on the vastus lateralis of the right thigh. Four 60-s work bouts (ranging from 200 to 400 W) were completed. Adequate rest was given between bouts to allow for the participants’ heart rate (HR) to drop within 10 beats of their resting HR. The EMG amplitude was averaged over 5-s intervals for each 60-s work bout. Resulting slopes from each successive work bout were used to calculate EMG FT. A 2-way ANOVA, Group (Cr vs. Pl) EETime (pre vs. post), resulted in a nonsignificant (p > .05) interaction for supplement and time. In addition, a significant increase (p = .009) in weight was observed in the Cr group. These data suggest that there was a minimal influence of Cr loading on EMG FT for the participants in this study.