Physiological responses and physical performance during football in the heat.

Magni Mohr,Sebastien Racinais,Justin Grantham,Lars Nybo,Maria Moran

doi:10.1371/journal.pone.0039202

Magni Mohr, Sebastien Racinais + Show 3 more

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https://doi.org/10.1371/journal.pone.0039202

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Abstract

PurposeTo examine the impact of hot ambient conditions on physical performance and physiological responses during football match-play.MethodsTwo experimental games were completed in temperate (∼21°C; CON) and hot ambient conditions (∼43°C; HOT). Physical performance was assessed by match analysis in 17 male elite players during the games and a repeated sprint test was conducted after the two game trials. Core and muscle temperature were measured and blood samples were obtained, before and after the games.ResultsMuscle and core temperatures were ∼1°C higher (P<0.05) in HOT (40.3±0.1 and 39.5±0.1°C, respectively) compared to CON (39.2±0.1 and 38.3±0.1°C). Average heart rate, plasma lactate concentration, body weight loss as well as post-game sprint performance were similar between the two conditions. Total game distance declined (P<0.05) by 7% and high intensity running (>14 km⋅h−1) by 26% in HOT compared to CON), but peak sprint speed was 4% higher (P<0.05) in HOT than in CON, while there were no differences in the quantity or length of sprints (>24 km⋅h−1) between CON and HOT. In HOT, success rates for passes and crosses were 8 and 9% higher (P<0.05), respectively, compared to CON. Delta increase in core temperature and absolute core temperature in HOT were correlated to total game distance in the heat (r = 0.85 and r = 0.53, respectively; P<0.05), whereas, total and high intensity distance deficit between CON and HOT were not correlated to absolute or delta changes in muscle or core temperature.ConclusionTotal game distance and especially high intensity running were lower during a football game in the heat, but these changes were not directly related to the absolute or relative changes in core or muscle temperature. However, peak sprinting speed and execution of successful passes and crosses were improved in the HOT condition.

Highlights

Playing football in the heat has been shown to result in high body temperatures [1,2,3], which may have a negative impact on performance and accelerate the development of fatigue during a game
Tm was higher (P,0.05) after the 1st half than after the 2nd half in control game (CON), while there was no difference between halves in hot ambient conditions (HOT) (Figure 1)
Our data showed that well-trained football players have a moderate reduction in total distance (7%) and a marked decline (26%) in the amount of high intensity running completed when a game is played in hot ambient conditions compared to a temperate environment

Summary

Introduction

Playing football in the heat has been shown to result in high body temperatures [1,2,3], which may have a negative impact on performance and accelerate the development of fatigue during a game. Ekblom [1] compared a game at moderate heat (30uC) to a game at a normal temperature (20uC), while Ozgunen et al [3] compared two games in the heat with only two degrees difference Neither of these studies could elucidate the physiological and performance responses of athletes normally competing in temperate conditions when exposed to severe heat stress (.40uC) which often occurs during international tournaments and will be expected at the upcoming football World Cup in Qatar in 2022. Mohr et al [2]

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