Outpaced by Industry: Industrial Environments Reduce Endurance, With Implications for Evolutionary Fitness.

OBJECTIVES: Physical function-the capacity to perform tasks requiring endurance and/or strength-is a key determinant of fitness that has directly influenced Homo sapiens' survival, reproduction and health throughout our evolutionary journey. However, the last 200-300 years of global industrialization has transformed human habitats at an unprecedented rate and may now be compromising key functions that underpin our fitness (Environmental Mismatch Hypothesis). Although industrialization has delivered a range of benefits, it has simultaneously introduced novel environmental challenges (e.g., air pollution, microplastics) and reduced contact with beneficial aspects of nature (e.g., phytoncides). While negative effects of industrialization have been demonstrated for other determinants of fitness, its impact on physical function remains almost completely unexplored.

MATERIALS AND METHODS: We conducted a randomized, counterbalanced crossover study to determine whether brief exposure to an industrialized environment would impair endurance performance relative to a forest environment (used as a proxy for non-industrial ancestral conditions). Twenty-five healthy adults (19 females, 6 males) completed two test sessions, each involving a 90 min environmental exposure followed by a standardized laboratory cycling test of endurance.

RESULTS: Endurance performance was significantly reduced following industrial exposure (time-to-exhaustion: 13.5 ± 0.9 min) compared to forest exposure (14.6 ± 1.0 min; p = 0.007). Industrial exposure also worsened mood and led to volitional exhaustion at a lower perceived exertion, while cardiorespiratory markers recorded during the endurance test (e.g., V̇O) did not differ significantly between conditions.

CONCLUSIONS: These results suggest that acute exposure to industrialized environments may reduce physical capacity, with potential consequences for evolutionary fitness.