Neuromuscular and cardiovascular responses of Royal Marine recruits to load carriage in the field

Cardiovascular and neuromuscular responses of 12 male Royal Marine recruits (age 22 ± 3 years, body mass 80.7 ± 6.8 kg, V˙O2max 52.3 ± 2.7 ml kg−1 min−1) were measured during 19.3 km of load carriage walking at 4.2 km h−1 and carrying 31.0 kg. Heart rate during load carriage was 145 ± 10 beats·min−1 (64 ± 5 %HRR) and showed a negative relationship with body mass (r = −0.72, P   = 0.009) but no relationship with V˙O2max (ml kg−1 min−1; r = −0.40, P = 0.198). Load carriage caused a decrease in vertical jump height (8 ± 9%) and power (5 ± 5%) (P < 0.001). Change in vertical jump power showed a positive relationship with body mass (r2 = 0.40, P   = 0.029) but no relationship to V˙O2max (ml kg−1 min−1; r2 = 0.13, P = 0.257). In conclusion, load carriage caused a reduction in vertical jump performance (i.e. decreased neuromuscular function). Lighter individuals were disadvantaged when carrying absolute loads, as they experienced higher cardiovascular strain and greater decreases in neuromuscular function.

► We examined the physiological responses of Royal Marines to load carriage.
► Participants walked 19.3 km at 4.2 km h−1 carrying 31 kg
► Load carriage caused neuromuscular impairment of the lower limbs.
► Heart rate and neuromuscular impairment were greater for lighter participants.
► The findings have implications for selection and training for load carriage tasks.