Do the Eyes tell the Truth? A Novel Approach to Monitoring Fatigue in Professional Basketball Players

Abstract

The impact of fatigue on athlete health and performance is of significant interest to the sport science community. Traditional fatigue and recovery monitoring tools have limitations in terms of invasiveness, cost, and time-consuming nature. Therefore, there is a need for alternative, non-invasive methods that provide reliable and valid measures of fatigue and recovery. Pupillometry, a technique that measures various aspects of the pupil in real-time, has emerged as a potential tool for fatigue detection. To explore its potential, the present thesis aimed to explored the underlying factors of NBA game-play performance, and explored the potential of handheld quantitative infrared pupillometers (HQIPs) as a tool for monitoring athlete fatigue and recovery in a professional women¿s basketball setting. More particularly, the pilot study examined the potential usefulness of a HQIP to monitor game-induced fatigue inside a professional female basketball setting by determining its (1) test-retest repeatability, (2) relationship with other biomarkers of game-induced fatigue, and (3) time-course from rested to fatigued states.. Method: A non-ophthalmologic practitioner performed a standardized Pupil Light Reflex (PLR) test using a medically graded HQIP among 9 professional female basketball players (2020¿2021 Euro Cup) at baseline, 24-h pre-game (GD-1), 24-h post-game (GD+1) and 48-h post-game (GD+2). This was repeated over four subsequent games, equaling a total of 351 observations per eye. Results: The results indicated that (1) jet lag, interrupted sleep schedules, and stress associated with frequent air travel negatively impact the physical and cognitive performance of professional basketball players, (2) a wide variety of factors l influence individual and collective game-play performance in professional basketball, including variables such as the age, gender, height and body mass index of the players as well as other contextual factors such as the playing style and tactical strategies all play a substantial role on NBA game-play performance, (3) Two out of seven pupillometrics displayed good ICCs (0.95¿0.99) (MinD and MaxD). Strong significant relationships were found between MaxD, MinD, and all registered biomarkers of game-induced fatigue (r = 0.69¿0.82, p < 0.05), as well as between CV, MCV, and cognitive, lower-extremity muscle, and physiological fatigue markers (r = 0.74¿0.76, p < 0.05). Three pupillometrics were able to detect a significant difference between rested and fatigued states. In particular, PC (right) (F = 5.173, ¿2 = 0.115 p = 0.028) and MCV (right) (F = 3.976, ¿2 = 0.090 p = 0.049) significantly decreased from baseline to GD+2, and LAT (left) (F = 4.023, ¿2 = 0.109 p = 0.009) significantly increased from GD-1 to GD+2. Discussion: The findings suggest that a non-ophthalmologic practitioner can effectively monitor pupillometrics in a reliable manner over a 5-week competition period. Five pupillometric measures (NPi, CV, MCV, MD, and MinD) showed promise in monitoring fatigue and recovery following games, with MCV showing the largest and most significant difference from baseline to two days after the game. However, it is important to note that these findings are based on a relatively small and homogenous sample. The study also demonstrated that HQIPs can be used by non-ophthalmologic staff members in a fast, practical, non-invasive, and reliable manner, without interfering with the team's schedule. This is beneficial for professional sports organizations where players often have limited recovery time between games. Future research should explore the applicability of these findings in different sports, teams, and competition formats. Conclusion: HQIPs have opened a new window of opportunity for monitoring game-induced fatigue in professional female basketball players. However, future research initiatives across larger and heterogenous samples, and longer investigation periods, are required to expand upon these preliminary findings