Training and match running distances and perceived exertion at sea-level and altitude in elite North American soccer: A natural longitudinal cross-over case series.

In a natural cross-over design we quantified responses to training and matches at sea-level and altitude. Total, and high-speed, running distance and differential session ratings of perceived exertion for breathlessness (sRPE-B) and leg exertion (sRPE-L) were collected from 19 professional soccer players (age: 27.3 ± 3.4 years, stature: 181.2 ± 5.9cm, mass: 78.7 ± 8.1kg) at sea-level and altitude. Data were collected for matches, and training one, and two, days pre-match. Differences between altitude conditions were estimated through mixed-linear modeling with 95% confidence intervals representing values highly compatible with our observed data. In matches, total distance may have been reduced (95% confidence intervals 43 to -833 m, surprisal [s] = 3.74) and sRPE-B may have increased (-0.6 to 10.7, s = 3.66) at altitude. A clear perceptual shift was observed with sRPE-B increasing relative to sRPE-L (-13.4 to -7.17, s >13) at altitude. Training at altitude included higher total (318 to 661 m, s > 13), and high-speed (33.1 to 93 m, s > 13), running distances but sRPE-L reduced (-14.2 to -1.01, s = 5.39) and sRPE-B increase relative to sRPE-L (-15.1 to -3.93, s = 10.3). Our key finding was breathlessness increased relative to leg exertion at altitude.