Effect of exercise in a desert environment on physiological and subjective measures.

Green exercise is beneficial to emotional and physiological measures, however, the US has large desert areas. We aimed to determine if exercise in a desert (brown) environment extends similar benefits to green. Participants (N = 10) completed baseline measures (PRE), 30-min seated rest (SIT), and 30-min self-paced walking (WALK) in: indoor, outdoor urban, green, and two brown environments. Heart rate (HR), blood pressure (BP), and measures of stress, comfort, and calm were obtained. After SIT, HR was elevated in urban vs green (p = 0.05). Systolic BP was lower after SIT compared to PRE and WALK (p = 0.05). Brown and green returned greater comfort and calm scores (p = 0.001). Stress was lower following WALK than PRE and SIT (p < 0.01). Comfort and calm were greatest in natural environments, and exercise significantly reduced perceived stress. Taken together, these data provide evidence that exercise in a desert environment is just a beneficial as the exercise performed in a green environment. Abbreviations: ANCOVA: analysis of covariance; ANOVA: analysis of variance; AU: arbitrary units; BP: blood pressure; BSL: below sea level; DBP: diastolic blood pressure; HR: heart rate; PRE: baseline measurement; PS: perceived stress; SBP: systolic blood pressure; SIT: measurement following 30-min seated rest; WALK: measurement following 30-min self-paced walking.

Reliability of Trail Walking and Running Tasks Using the Stryd Power Meter.

Footpod monitors are wearable devices attaching to the shoe with the ability to sense oscillations in leg movement; however, few studies provide reliability. The purpose was to provide reliability data for outdoor tasks as measured by the Stryd Power Meter, which is a footpod monitor. Young healthy individuals (N=20, male n=12, female n=8) completed two 5-min self-paced walks along a trail, and two 5-min trail runs. Reliability of the tasks was determined using Coefficient of Variation (CV), Intraclass Correlation (ICC), and 95% confidence intervals (CI). Measures during trail running that returned a CV less than 10%, met the ICC threshold of 0.70, and displayed good to excellent 95% CI included pace, average elapsed power, average elapsed form power, average elapsed leg spring, and vertical oscillation. The only variable during walking to meet these criteria was maximal power (CV=4.02%, ICC=0.968, CI=0.902, 0.989). Running tasks completed on a trail generally return more consistent measures for variables that can be obtained from the Stryd footpod device than walking tasks.

Chronotype and Social Jetlag Influence Performance and Injury during Reserve Officers' Training Corps Physical Training.

Sleep and circadian rhythms are critically important for optimal physical performance and maintaining health during training. Chronotype and altered sleep may modulate the response to exercise training, especially when performed at specific times/days, which may contribute to musculoskeletal injury. The purpose of this study was to determine if cadet characteristics (chronotype, sleep duration, and social jetlag) were associated with injury incidence and inflammation during physical training. Reserve Officers' Training Corps (ROTC) cadets (n = 42) completed the Morningness/Eveningness Questionnaire to determine chronotype, and 1-week sleep logs to determine sleep duration and social jetlag. Salivary IL-6 was measured before and after the first and fourth exercise sessions during training. Prospective injury incidence was monitored over 14 weeks of training, and Army Physical Fitness Test scores were recorded at the conclusion. Chronotype, sleep duration, and social jetlag were assessed as independent factors impacting IL-6, injury incidence, and APFT scores using ANOVAs, chi-squared tests, and the t-test where appropriate, with significance accepted at p < 0.05. Evening chronotypes performed worse on the APFT (evening = 103.8 ± 59.8 vs. intermediate = 221.9 ± 40.3 vs. morning = 216.6 ± 43.6; p < 0.05), with no difference in injury incidence. Sleep duration did not significantly impact APFT score or injury incidence. Social jetlag was significantly higher in injured vs. uninjured cadets (2:40 ± 1:03 vs. 1:32 ± 55, p < 0.05). Exercise increased salivary IL-6, with no significant effects of chronotype, sleep duration, or social jetlag. Evening chronotypes and cadets with social jetlag display hampered performance during morning APFT. Social jetlag may be a behavioral biomarker for musculoskeletal injury risk, which requires further investigation.