Figure 1. Heart rate and mean arterial pressure responses to static handgrip.

Mean (± s.e.m.) responses to static handgrip sustained to fatigue at 40 % of maximal voluntary contraction, followed by 2 min post-handgrip circulatory arrest pre-flight (n = 5), in-flight (n = 4) and post-flight (n = 5). Data were averaged for 1 min of baseline, 1 min of the initial static handgrip, the last 30 s of handgrip prior to fatigue (presented as ‘at fatigue’), the intermediate period after the initial 1 min and before the last 30 s of handgrip and for each 1 min of post-handgrip circulatory arrest and recovery. There were no significant differences in responses on Earth and in space. BL, baseline; HG₁, first minute of static handgrip; HG_i, intermediate handgrip period; HG_F, static handgrip at fatigue; C₁ and C₂, first and second minutes of post-handgrip circulatory arrest; R₁ and R₂, first and second minutes of recovery. * P < 0.05 and ** P < 0.01, compared with baseline pre-, in- and post-flight.