Abstract
This study investigated whether an 8-week running program would improve measures of lower-extremity power and balance with a single subject design. The running program consisted of alternating 2-week periods of running on even road surfaces and running on uneven, natural trails. It was hypothesized that the increased loading forces and neuromuscular control necessary to navigate the uneven terrain in the trail running condition would increase both strength and balance measures. The participant was a healthy, physically active 45 year old male who did not currently meet the ACSM guidelines of 150 min/week of moderate or 75 min/week of vigorous exercise but was not unfamiliar with endurance running exercise. Balance ability was measured using the y-balance test in the anterior (ANT), posteromedial (PM), and posterolateral (PL) directions. The vertical jump test was used as a proxy for lower-extremity power. Where statistically appropriate, an interrupted time series analysis was conducted to compare experimental to baseline values and interventional phases to each other. It was found that the road running phases increased vertical jump height while trail running decreased them. Trail running increased y-balance scores in the PL direction only, while balances score improvements in the other test directions decreased or remained the same. The correlation between vertical jump height and balance scores was moderately sized (r = .56) but did not reach significance (p = .09). It was found that in this subject the road running program consistently improved power while the trail running program consistently decreased power. It was also observed that the changes in balance did not follow the changes in power and suggest that power and balance do not change consistently with each other.