The present study assessed the effect of 6 • head-down (establishing the cephalad fluid displacement noted in astronauts in microgravity) prone (simulating the effect on the eye) tilt during rest and exercise (simulating exercise performed by astronauts to mitigate the sarcopenia induced by unloading of weight-bearing limbs), in normocapnic and hypercapnic conditions (the latter simulating conditions on the International Space Station) on intraocular pressure (IOP).Volunteers (mean age = 57.8 ± 6 years, n = 10) participated in two experimental sessions, each comprising: (i) 10 min rest, (ii) 3 min static handgrip exercise (30% max), and (iii) 2 min recovery, inspiring either room air (NCAP) or a hypercapnic mixture (1% CO 2 , HCAP). We measured IOP in the right eye, cardiac output (CO), stroke volume (SV), heart rate (HR) and mean arterial pressure (MAP) at regular intervals. Baseline IOP in the upright seated position while breathing room air was 14.1 ± 2.9 mmHg. Prone 6 • head-down tilt significantly (P < 0.01) elevated IOP in all three phases of the NCAP (rest: 27.0 ± 3.7 mmHg; exercise: 32.2 ± 4.8 mmHg; recovery:27.4 ± 4.0 mmHg) and HCAP (rest: 27.3 ± 4.3 mmHg; exercise: 34.2 ± 6.0 mmHg; recovery:29.1 ± 5.8 mmHg) trials, with hypercapnia augmenting the exercise-induced elevation in IOP (P < 0.01). CO, SV, HR and MAP were significantly increased during handgrip dynamometry, but there was no effect of hypercapnia. The observed IOP measured during prone 6 • HDT in all phases of the NCAP and HCAP trials exceeded the threshold pressure defining ocular hypertension. The exercise-induced increase in IOP is exacerbated by hypercapnia.

Moderate‐intensity exercise sessions are incorporated into heat‐acclimation and hypoxic‐training protocols to improve performance in hot and hypoxic environments, respectively. Consequently, a training effect might contribute to aerobic performance gains, at least in less fit participants. To explore the interaction between fitness level and a training stimulus commonly applied during acclimation protocols, we recruited 10 young males of a higher (more fit‐MF, peak aerobic power [VO2peak]: 57.9 [6.2] ml·kg−1·min−1) and 10 of a lower (less fit‐LF, VO2peak: 41.7 [5.0] ml·kg−1·min−1) fitness level. They underwent 10 daily exercise sessions (60 min@50% peak power output [Wpeak]) in thermoneutral conditions. The participants performed exercise testing on a cycle ergometer before and after the training period in normoxic (NOR), hypoxic (13.5% FiO2; HYP), and hot (35°C, 50% RH; HE) conditions in a randomized and counterbalanced order. Each test consisted of two stages; a steady‐state exercise (30 min@40% NOR Wpeak to evaluate thermoregulatory function) followed by incremental exercise to exhaustion. VO2peak increased by 9.2 (8.5)% (p = .024) and 10.2 (15.4)% (p = .037) only in the LF group in NOR and HE, respectively. Wpeak increases were correlated with baseline values in NOR (r = −.58, p = .010) and HYP (r = −.52, p = .018). MF individuals improved gross mechanical efficiency in HYP. Peak sweat rate increased in both groups in HE, whereas MF participants activated the forehead sweating response at lower rectal temperatures post‐training. In conclusion, an increase in VO2peak but not mechanical efficiency seems probable in LF males after a 10‐day moderate‐exercise training protocol.

A series of studies were conducted to test the hypothesis that compression socks (uniform or graduated compression) worn after exercise mitigate exercise-induced pain. Fifty-nine (59) participants took part in three separate exercise protocols to induce a degree of muscle soreness from low to severe. Participants wore either ankle height socks with no compression (NoCo), knee height socks with uniform (UNI) or graduated compression (GRAD) for 8 h/day following exercise. Before, immediately after and during recovery, we measured muscle strength, flexibility and the perception of pain. The three exercise protocols were as follows. (1) Hike: compared the effects of GRAD and NoCo socks following a 10-km treadmill hike with a 1000 m ascent and descent. (2) Trail Run: compared the effect of GRAD and UNI following a 14-km trail run with 250 m ascent and descent. (3) Calf Exercise: compared the effect of GRAD and UNI socks with a predominately eccentric calf exercise. GRAD socks significantly mitigated the perception of calf pain compared to NoCo (Hike). The UNI socks were superior to the GRAD socks in mitigating the perception of pain during recovery in the Trail Run. No statistical difference was noted between UNI and GRAD socks after the Calf Exercise. Compression socks mitigated the perception of calf muscle pain (Hike trial), with UNI providing more benefit compared to GRAD socks (Trail Run trial). No differences between the UNI and GRAD socks were observed in the Calf Exercise trial. Compression socks aid in the perception of recovery following low to moderate pain from delayed onset muscle soreness.