Andrew Clark’s scientific contributions

Purpose: This study investigated the relationship between travel demands and match loads on perceptual recovery, fatigue, and sleep following postmatch travel in national football teams. In addition, the influence of travel demands and the time between match kickoff and travel departure on postmatch recovery was examined. Methods: Match-running load (via GPS) and travel data were obtained from 79 male national-team footballers. Postmatch travel duration, direction, context, time-zone difference, and time between kickoff and travel departure were collated. Athletes provided perceptual ratings of fatigue, soreness, sleep, stress, and recovery from 1 day prematch through to 3 days after postmatch travel. Linear mixed models assessed the influence of match load and travel on perceptual ratings for 3 days posttravel. Additional models assessed a standardized postmatch time point of match day + 3 to determine whether timing and extent of travel influenced recovery. Results: Higher match loads were associated with poorer recovery, fatigue, soreness, and sleep (P = .001-.032). Athletes reported poorer fatigue, soreness, and recovery when traveling from national teams back to clubs compared with between national-team matches (P < .001). Traveling eastward was associated with poorer sleep (P = .004). Longer periods between kickoff and travel departure were associated with poorer sleep on match day + 3 (P = .003). Conclusions: Perceptual recovery, fatigue, sleep, and soreness following postmatch travel were affected by both match load and travel demands. Greater match loads and eastward postmatch travel may impair recovery. In addition, departing later after a match was associated with poorer sleep on match day + 3; however, no relationships existed to any other recovery measures.

Purpose: This study examined the relationship of prematch travel and in-camp training on ensuing physical and technical match performance of footballers (soccer) competing for a national team. Methods: Match running and technical performance data were obtained from 68 national-team footballers competing in international matches (N = 108). Match performance data were aligned with the confirmed travel durations, time-zone change, travel direction, and time between arrival and kickoff for the travel to the match. In addition, in-camp training load from the 3 days prior to national-team matches was also collated. Linear mixed models assessed relationships between travel and training measures with physical and technical match performance outcomes. Results: Travel variables explained little variance in outcomes (R2 = .02-.16). Traveling eastward was associated with an increase in total (P = .042) and very high-speed distance (P = .030) in matches and a 5% decrease in pass accuracy (P = .012). Greater time-zone difference was associated with increased match decelerations (P = .027), while arriving later for matches was associated with increased total (P = .041) tackles. Increases in training high-speed distance were associated with increases in match high-speed distance (P = .004) and number of decelerations (P < .001). An increase in training total distance was associated with a decrease in match decelerations (P = .002). Conclusions: Prematch travel appeared to have minimal effects on physical and technical performance in this national team. Training loads prior to matches may have some relationship with match running performance, and, thus, readiness to train should be a priority for athletes arriving in national-team camps.

INTRODUCTION & AIMS International footballers (soccer) are regularly required to travel directly from club to national team with only a few days to recover and prepare for matches. The combined stress of travel and training loads may therefore influence match performance. This research aims to examine the relationship of pre-match travel and in-camp training on ensuing physical and technical match performance of footballers competing for a national team. METHODS Match running and technical performance data were obtained from 68 national team footballers competing in international matches (n=108). Match performance data was aligned with confirmed travel durations, time zone change, travel direction, and the time between arrival and kick-off for travel into the match. Additionally, in-camp training loads for GPS for the 3 days prior to national team matches were also collated. Linear mixed models assessed relationships between travel and training measures with physical and technical match performance outcomes. RESULTS Travel variables explained little variance in outcomes (R2=0.02-0.16). Travelling eastward was associated with an increase in total (p=0.042) and very high-speed distance (p=0.030) in matches and a 5% decrease in pass accuracy (p=0.012). Greater time zone difference was associated with increased match decelerations (p=0.027), while arriving earlier for matches was associated with decreased total tackles (p=0.041). Increases in training high-speed distance were associated with increases in match high-speed distance (p=0.004) and number of decelerations (p<0.001). An increase in training total distance was associated with a decrease in match decelerations (p=0.002). CONCLUSIONS Pre-match travel appeared to have minimal effects on physical and technical performance in this national team, especially given most players arrived at least 40h prior to matches. Training loads prior to matches may have some relationship with match running performance and thus readiness to train should be a priority for athletes arriving in national team camps.

Purpose: This study examined posttravel perceptual responses of national-team footballers (soccer) following different flight paths, arrival/departure times, and trip contexts. Methods: Details of 396 flights from national-team players (N = 68) were obtained and verified via an online flight database. Each player provided ratings of perceptual fatigue, sleep, soreness, stress, and jet lag for 2 days before and after each trip. The flight path (continents of departure and arrival), travel context (into vs out of national team), and arrival and departure times were obtained for each trip. Linear mixed models compared the pretravel with posttravel change in perceptual responses based on flight path, context, and schedule. Results: Perceived jet-lag ratings were more responsive to travel variables (R2 = .48) than other perceptual ratings (R2 < .26). Travel from Asia to Europe (P < .05) and Europe to Australia (P < .001) had significantly higher jet-lag ratings than all other paths. Fatigue scores were worst following Asia to Europe (P < .05) and Europe to Australia (P < .05) travel, while sleep scores were worst following Europe to Australia travel (P < .01). Perceptual responses were poorer following travel from national team to club compared with all other travel contexts (P < .05). Arrival during the daytime (11 AM to 5 PM) resulted in better perceptual responses than early-morning or late-night arrivals (P < .05). Conclusions: Perceived jet-lag ratings are more responsive to travel demands than perceptual wellness scales in national-team football athletes. Poorer perceptual responses may be expected when travel is longer in nature, ends later in the day, or involves travel out of the national team back to club.

Purpose: This study investigated the association between (1) time zone difference and (2) travel direction (east vs west) with posttravel changes in perceptual responses of national-team footballers. Methods: Travel schedules from 355 national-team trips (50 elite soccer players) were verified using an online flight database. All players provided perceptual ratings of fatigue, sleep quality, soreness, and stress to calculate changes in scores up to 2 days after travel. Trips were categorized as <3, 3 to 6, 6 to 9, or 9+ time zone changes, along with travel direction (eastward or westward). The pretravel to posttravel changes in perceptual ratings at days 1 and 2 postarrival were compared between time zone change and travel direction with linear mixed models. Results: For every time zone crossed, poorer ratings of perceptual fatigue (β = 0.068, P < .001), sleep (β = 0.095, P < .001), soreness (β = 0.0049, P < .001), and total wellness (β = 0.214, P < .001) were observed. However, the models explained only small proportions of the variation in postflight perceptual responses (7%-18%). Regardless, travel across 9+ time zones resulted in significantly worse perceived fatigue, sleep, and total wellness for days 1 and 2 postarrival compared with travel with <6 time zones (P < .05). Additionally, fatigue, sleep, and total scores were worse on day 2 following trips of 9+ time zones. Eastward travel resulted in poorer sleep ratings (β = 0.52, P < .001) than westward travel within time zone groupings. Conclusions: Perceptual ratings of fatigue and sleep become progressively worse as travel increases in national-team soccer players, especially after travel across 9+ time zones and eastward travel.

Elite football (soccer) involves club, continental and international fixtures, requiring players to undertake extensive travel [1]. For a national football federation, this includes the transport of players between club and camp/tournament commitments, which is often a point of contention between respective organisations [2]. Partly this contention results from the effects of travel, whereby jet lag and travel fatigue can negatively affect physical performance [3-5] and athlete wellbeing [6, 7]. Given the scarcity of data on elite players following travel, an initial step for any national football federation is to understand the volume and nature of travel undertaken by national team players. Such insight may better identify the schedule, timelines and needs of athletes' post travel. Better awareness of these travel needs can help maximise availability for training and minimise the impact of travel related stresses on performance or wellbeing. However, the regularity and volume of travel to national football team commitments has not previously been described. Further, travel demands are likely to vary significantly based on the location of the athlete and the national team camp. For countries outside of Europe, such as Australia, the travel demands and ensuing effects on player preparation can be substantial for both arrival into national team and on return to clubs [7]. Hence, detailed information regarding the type, frequency, and extent of travel for national team duties is important to aid in planning optimal travel schedules and interventions to assist players for international or club duty.