Competing at Altitude Reduces In-Match Physical Demands of Professional Soccer Players Compared With Sea Level

Purpose: This study examined whether physical demands during soccer matches differ between sea level and altitude, considering variations by playing position. Methods: Thirty-seven professional players were monitored during 22 matches (11 at sea level and 11 at altitudes of 2200–4090 m) with global navigation satellite systems. Independent mean differences were used to compare in-match physical demands (ie, total distance, distance covered at specific speed intervals, accelerations [ACCs] and decelerations [DECs], and maximal speed) between locations for 5 playing positions (central defenders, fullbacks, central midfielders, wide midfielders, and forwards). Results: At altitude, players covered shorter total distances (P < .001) and less distance in the 14.4- to 19.8-km/h (P < .001), 19.8- to 25.2-km/h (P < .001), and >25.2-km/h (P < .001) speed ranges. They also performed fewer ACCs (2.0–3.5 m/s², P < .001; 3.5–6.0 m/s², P < .001) and DECs (−3.5 to −2 m/s², P < .001; −6.0 to −3.5 m/s², P < .001) and achieved lower maximal speeds (P < .001). The impact of altitude varied by position: Central midfielders showed reduced performance in all variables, while central defenders (distance > 25.2 km/h, ACCs [2.0 and 3.5 m/s²], DECs [−3.5 and −2.0 m/s²], and maximal speed), fullbacks (distance > 25.2 km/h, ACCs, and DECs [−3.5 and −2.0 m/s²]), and forwards (distances [total, 19.8–25.2 km/h, and >25.2 km/h] and ACCs [−3.5 and −6.0 m/s²]) presented unclear differences (P > .05) between locations. Conclusion: Our study highlights the importance of considering playing positions when assessing the in-match activity profiles of sea-level resident soccer players competing at moderate to high altitudes.