How do travel and thermal conditions relate to away-team performance in the Chinese Super League?

This study examined whether travel direction, travel distance, opponent strength and match-site thermal conditions were associated with the performance of away teams in the Chinese Super League. Data from 701 away matches from 2017 to 2019 were obtained from Amisco Pro. Seventeen technical and physical indicators were reduced by principal component analysis to four match-performance dimensions, accounting for 67.9% of the variance. Linear mixed-effects models were estimated for away-team goal difference and for each dimension, with travel category, geodesic distance, pre-match Elo difference, temperature, relative humidity and their interaction specified in a single model. Neither travel category (F(3, 150.9) = 1.19, p = .317) nor geodesic distance (β = 0.066 goals per SD, 95% CI [−0.101, 0.233]) was clearly associated with goal difference. A 1-SD increase in home-minus-away pre-match Elo difference was associated with a 0.771-goal reduction in away-team goal difference (95% CI [−0.912, −0.630]). Higher temperature (β = −0.455 SD, 95% CI [−0.556, −0.353]) and relative humidity (β = −0.142 SD, 95% CI [−0.217, −0.067]) were associated with lower running volume and high-speed activity, with a negative temperature-by-humidity interaction (β = −0.135 SD, 95% CI [−0.191, −0.079]). Thermal conditions were not clearly associated with goal difference. Northward and southward journeys involved substantial origin-to-destination thermal contrasts, but these provided no clear information beyond match-site conditions.