Thirty-nine healthy carriers (23–57 years of age) were
investigated in underground manual coal mines in
West Bengal, India during two different work spells of
a single work shift. We compared physiological strain of
workers less than 40 and greater than or equal to 40 years of age. For both groups,
mean heart rate was 124–133 beats/min, with a mean
corresponding relative cardiac cost of 50–66%. Maximum
aerobic capacities were estimated indirectly, following
a standard step test protocol. Average oxygen
consumption was 1.07–1.1 l/min, with an energy
expenditure of 5.35–5.5 kcal/min among both age
groups. Acceptable levels of physiological strain were
well encroached, and older workers faced the maximum
burden. The tasks studied were heavy to very
heavy in nature. The weight of load carriage at a spontaneously
chosen speed and the prevailing environmental
conditions merit serious attention. There is
extreme need of ergonomic interventions in reducing
the postural load and musculoskeletal discomforts in
this population.