News & Views from the Editor-in-Chief - L. Bruce Gladden
As usual, I have selected three excellent articles in this month's issue. First, Kaur and colleagues reported that rapid onset vasodilation induced by a single contraction of the forearm muscles was significantly attenuated in non-Hispanic black men, compared to white men, and this attenuation was evident even at low-intensity muscle contractions. The authors also reported reduced vasodilation to forearm cuff inflation, which was used to examine the contribution of the mechanical compression that occurs during muscle contraction. Collectively, these findings suggest an overall reduced ability to rapidly vasodilate in black men that is independent of large systemic cardiovascular changes and muscle metabolism. The extent to which this attenuated hyperemia at the immediate onset of exercise might contribute to lower blood flow responses previously observed during steady-state handgrip exercise in black men warrants further investigation.
Next, Conway et al. tested the efficacy of six weeks of horizontal impeding force during walking in older adults. The training was designed to mitigate age-related deficits in gait performance. Walking with impeding forces augments the mechanical output required from muscles spanning the ankle during the push-off phase. Their results showed that, following training, older adults increased their isometric calf muscle strength by 18%, maximum walking speed by 10%, and 6-min walk distance by 9%. Participants also improved their habitual gait performance, increasing peak ankle moment and power output during push-off by 10%–15%. These findings suggest that training with horizontal impeding forces in older adults improves maximum muscular capacity while encouraging access to newfound strength gains, thereby improving habitual push-off intensity during walking.
Finally, it is known that tolerance to exercise and fatigue is influenced by many factors, with critical power/critical speed being among the most important and arguably, least studied. In their study, Gifford and Collins provide evidence that the critical-speed threshold continuously decreases after age 35 with greater rates of decline occurring between 35 and 45, and especially after 70. Despite the large decrease in critical speed with age, the relationship between race pace for various events and critical speed remained constant with age. This highlights the close relationship between this threshold, and pacing and exercise tolerance throughout aging.
L. Bruce Gladden
School of Kinesiology