Photoplethysmography Detection of Overreaching

Introduction Detecting the onset of functional or non-functional overreaching in endurance athletes is of prior importance to ensure reactive amendment of the scheduled training program. The objective of this study was to assess photoplethysmography (PPG) in overloaded athletes and test whether 1) it would be affected differently in functional overreached (FOR) or non-overreached acutely fatigued (AF) athletes; 2. Specific PPG characteristics would allow timely distinction of FOR and AF. Methods Fifteen athletes performed 2-wk baseline (BSL) training followed by 3-wk overload (+45%; OVL) and 2-wk recovery (-20%; RCV). 3000 m running time-trial was used to assess performance at the end of BSL, OVL and RCV and distinguish FOR and AF. PPG was recorded overnight using a wearable sensor, every third night. Overnight means and variances of systolic, diastolic and dicrotic amplitudes and times as well as systolic and diastolic slopes were used to discriminate FOR and AF athletes. Results Performance was decreased in FOR and improved in AF at the end of OVL. Diastolic time was greater in AF than FOR whilst systolic slope was smaller in AF than FOR during OVL. The variances of systolic, diastolic, dicrotic amplitudes, systolic, diastolic slopes and pulse areas were smaller in AF compared to FOR in the last week of OVL. Conclusion PPG is an efficient tool for the detection of overreaching as it distinguished FOR and AF athletes during OVL (prior performance decrement). This fast-responding method would therefore allow adjusting the daily training content in order to prevent non-functional overreaching. Address for correspondence: Nicolas Bourdillon, ISSUL, Institute of Sport Sciences, Synathlon, University of Lausanne, 1015 Lausanne, Switzerland. Tel.: +41 21 692 3797. E-mail: nicolas.bourdillon@unil.ch NB and GPM have no conflicts of interest, sources of funding, or financial ties to disclose and no current or past relationship with companies or manufacturers who could benefit from the results of the present study. MN is an employee of my-vitality. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. This work was made possible by the financial support of the CTI commission n° 18164.2 PFLS-LS. Results of the present study do not constitute endorsement by ACSM. Accepted for publication October 2018. © 2018 American College of Sports Medicine

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