Abstract
Physical inactivity among adolescents is a growing health concern. Innovative, engaging interventions are needed, such as after-school programs to promote physical activity and improve youths’ health, including muscular fitness. PURPOSE: The purpose was to evaluate the impact of an outdoor physical activity intervention on muscle strength, muscle endurance, and agility in middle school students. METHODS: The intervention included various physical activities (e.g., kayaking, orienteering/hiking, archery, disc golf, mountain biking), across 10 sessions over 5 weeks. Seven 6th and 7th graders (age: 11.7 ± 0.2 years; BMI: 24.7 ± 2.7) completed pre and post intervention assessments for muscle strength, muscle endurance, and agility. A portable isometric dynamometer (Microfet 2; Hoggan Scientific, Salt Lake City, UT) was used to measured muscular strength and muscular endurance of leg (knee extension) and arm (shoulder extension) musculature. For both muscle groups, participants pushed as hard as possible against the dynamometer for 3s, rested for 3s, and repeated this cycle for 20 repetitions. Verbal encouragement was provided. Strength was defined as the maximum force produced during the 20 contractions. Muscular endurance was calculated using fatigue index (FI), calculated by dividing the minimum force produced by the maximum force. Muscular endurance is also expressed as a percent change from the maximum contraction force to the lowest force produced during the last five contractions. Participants also performed the agility T-test, completing two trials with 30s rest between trials. The fastest time was used for analysis. T-tests were used to determine statistical significance for pre-post changes, and Cohen’s d (effect size) was calculated to determine the practical meaningfulness of these changes. Data are reported as mean ± SE. RESULTS: While t-tests were not significant, effect sizes indicated small or medium effects for 5 of 7 variables. Leg strength improved from pre (39.40 ± 4.52 lbs) to post (48.23 ± 6.79 lbs) with a medium effect (d = 0.61; p = 0.156), and arm strength also increased from pre (18.74 ± 4.32 lbs) to post (20.46 ± 3.75 lbs) with a medium effect (d = 0.56; p = 0.191). Leg muscular endurance improved from pre (FI: 0.57 ± 0.06) to post (FI: 0.64 ± 0.06) with a medium effect (d = 0.52; p = 0.217), while there was no change in muscular endurance of the arm: pre (FI: 0.67 ± 0.03) and post (FI: 0.67 ± 0.04) (d = 0.04; p = 0.912). Leg endurance expressed as percent change showed an improvement from pre (-27.44 ± 5.83%) to post (-19.61 ± 5.04%) with a small effect (d = 0.33; p = 0.420), while the percent change in arm endurance was stable pre (-20.55 ± 3.56%) and post (-21.77 ± 3.61%) (d = 0.13; p = 0.745). Agility improved from pre (16.42 ± 1.18s) to post (15.87 ± 0.78s) with a small effect size (d = 0.38; p = 0.353). CONCLUSION: Results demonstrate that the outdoor physical activity intervention had a meaningful impact on leg strength and endurance, arm strength, and agility, while the effects on arm muscular endurance remained stable. Activities involved hiking hills and biking, which likely contributed to lower extremity improvements. Future programs should focus on enhancing muscular fitness through diverse outdoor physical activities that incorporate both lower and upper extremities. Funding: Social Innovation Research Accelerator Grant, Texas State University to LK, JM, KG.
Recommended Citation
Khan, Khizra; Mettler, Joni A.; Griffin, L. Kent; and Kipp, Lindsay E.
(2025)
"Impact of an Outdoor Physical Activity Intervention on Muscular Fitness in Adolescents,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
17, Article 91.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss17/91
Included in
Health and Physical Education Commons, Medical Education Commons, Sports Sciences Commons