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

Purpose: Real-world data on perceptions of exertion in professional soccer at altitude are limited. Over four years, we quantified responses to training and matches at sea level and altitude using a natural repeated-measures, crossover design.
Methods: Forty-one male professional soccer players (27.3 ± 3.4 years; 181.2 ± 5.9 cm; 78.7 ± 8.1 kg) from a single club completed two training sessions and one match within 96 hours of arriving at altitudes between 1356–2300 m. Running distances (total and high-speed >5.6 m/s) were measured via a Global Positioning System (Catapult Optimeye S7). Differential session ratings of perceived exertion for breathlessness (s-RPE-B) and leg exertion (s-RPE-L) were collected at sea level and altitude. Data were gathered for matches and training sessions one and two days pre-match.
Results: Estimates were derived from mixed-linear modeling with 95% confidence intervals (CI) and surprisal [s] values computed. A s-value of 4.2 would indicate our observed data are no more surprising than flipping four consecutive heads with a fair coin, providing four bits of information against the null. In matches, total distance (42 observations | 20 players) may have decreased (95% CI; 43 to -833 m, s = 3.74), and s-RPE-B (36 | 18) may have increased (-0.6 to 10.7, s = 3.66) at altitude. A perceptual shift was observed: s-RPE-B increased relative to s-RPE-L (-13.4 to -7.17, s > 13). Training at altitude showed higher total (318 to 661 m, s > 13) and high-speed (33.1 to 93 m, s > 13) running distances (84 | 36), while s-RPE-L decreased (-14.2 to -1.01, s = 5.39) and s-RPE-B increased relative to s-RPE-L (-15.1 to -3.93, s = 10.3 [67 | 32]).
Conclusions: Our exploratory observations indicate a shift in players’ perceptions of exertion, increasing breathlessness relative to leg exertion during acute visits to altitude.