Jasmien Dumortier

Possible Influences on the Interpretation of Functional Domain (FD) Near-Infrared Spectroscopy (NIRS): An Explorative Study:

The influence of subcutaneous adipose tissue (ATT) and oxygen (O2) delivery has been poorly defined in frequency domain (FD) near-infrared spectroscopy (NIRS). Therefore, the aim of this study was to investigate the possible influence of these variables on all FD NIRS responses using a reliable protocol. Moreover, these influences were also investigated when using relative oxy- and deoxyhemoglobin and -myoglobin (oxy[Hb + Mb] and deoxy[Hb + Mb]) values (in %). A regression analysis was carried out for ATT and maximal–minimum oxy[Hb + Mb], deoxy[Hb + Mb], oxygen saturation (SmO2), and total hemoglobin (totHb) amplitudes during an incremental cyclic contraction protocol (ICCP) in a group of 45 participants. Moreover, the same analysis was carried out between subcutaneous ATT and the relative oxy- and deoxy[Hb + Mb] values (in %). In the second part of this study, a regression analysis was performed for peak forearm blood flow (FBF) during ICCP and the absolute and relative NIRS values in a group of 37 participants. Significant exponential correlation coefficients were found between ATT and deoxy[Hb + Mb] (r = 0.53; P < 0.001), oxy[Hb + Mb] (r = 0.57; P < 0.001), and SmO2 amplitudes (r = 0.57; P < 0.001). No significant relations were found between ATT and relative oxy[Hb + Mb] (r = 0.37; P = 0.07) and deoxy[Hb + Mb] (r = 0.09; P = 0.82). Significant positive correlation coefficients were found between force at exhaustion and maximal FBF (r = 0.66; P < 0.001), maximal differences in deoxy[Hb + Mb] (r = 0.353; P = 0.032) and totHb (r = 0.512; P = 0.002) while no significant correlation coefficients were found between these maximal force values and maximal differences in oxy[Hb + Mb] (r = −0.267; P = 0.111) and SmO2 (r = −0.267; P = 0.111). Significant linear correlation coefficients were found between FBF and deoxy[Hb + Mb] (r = 0.51; P = 0.001), oxy[Hb + Mb] (r = −0.50; P = 0.001), SmO2 (r = −0.54; P = 0.001), and totHb amplitude (r = 0.61; P < 0.001). No significant correlations were found when using relative oxy[Hb + Mb] (r = −0.01; P = 0.957) and deoxy[Hb + Mb] (r = −0.02; P = 0.895). Based on these findings, caution is advised when using NIRS values, as subcutaneous ATT and O2 delivery significantly influence NIRS measurements. To eliminate these influences, use of relative deoxy[Hb + Mb] is advised, especially in clinical settings or in people with a higher subcutaneous ATT layer.

Forearm muscle oxygenation responses during and following arterial occlusion in patients with mitochondrial myopathy.

The aim was to study whether mitochondrial myopathy induces different oxygenation (deoxy[Hb+Mb] and oxy[Hb+Mb]) responses during and following arterial occlusion. In 10 mitochondrial myopathy patients (MMpatients) (age: 29±7 years; body mass: 59.9±15.7kg; heigth: 166.2±11.4cm) and age- and gender-matched healthy subjects (age: 28±9 years; body mass: 72.7±16.9kg; height: 174.4±8.7cm) arterial occlusion was performed by inflating a cuff to 240mmHg. Deoxy[Hb+Mb] and oxy[Hb+Mb] were registered during (AOoxy and AOdeoxy) and following (POdeoxy and POoxy) arterial occlusion. Amplitude of AOdeoxy did not differ (p=0.47) between MMpatients (44.9±28.0μM) and healthy subjects (38.6±22.8μM), The time constant of the exponential model was greater in MMpatients (263.4±49.1s vs. 200.3±73.7s, p=0.03). Following cuff release, in both populations a transient increase in total[Hb+Mb] was observed induced by different kinetics of POoxy and POdeoxy. The increase in POoxy (TD=6.6±2.2s and 11.9±3.5s; τ=3.8±1.4s and 6.4±2.9s for MMpatients and healthy subjects, respectively) was faster (p<0.001 for TD and τ) compared to the decrease in POdeoxy (TD=13.2±3.6s and 26.5±4.6s; τ=-6.2±2.2s and -9.6±2.4s for MMpatients and healthy subjects, respectively). POoxy and POdeoxy showed faster kinetics (p<0.001 and p<0.01 for TD and τ, respectively) in MMpatients compared to healthy subjects. MMpatients display altered oxygenation responses during and following arterial occlusion reflecting pathology related changes in the relationship between muscle blood flow and oxygen uptake.

Sleep, training load and performance in elite female gymnasts

Abstract Training load (TL) and recovery should be in optimal balance to obtain maximal performance gains. We aimed to study sleep as a recovery technique and its relationship with TL and performance in elite athletes. Twenty-six elite female artistic gymnasts were divided into an under 13 (n = 6), an under 14 (n = 6), a junior (n = 7; 14–15y) and a senior (=World Championship (WC) competitors, n = 7; ≥16y) category. Sleep, through sleep logs, and training parameters, using the session Rate of Perceived Exertion (sRPE) scale, were monitored to calculate total sleep time (TST), sleep efficiency (SE), TL, monotony and strain. Performance of WC competitors was evaluated through coach and WC qualification ranking. For the entire group, TST (effect sizes (ES) = −1.12, confidence intervals (CI) = −60:−47, P < .05) and SE (ES = −0.13, CI = −1.40:−0.10, P = .022) were shorter during week than weekend nights. TST and SE were highest in youngest gymnasts (P < .05). TL was lowest in under 13 and senior gymnasts (P < .05), while TL, monotony and strain were highest in junior gymnasts (P < .05). A negative regression was found between TST and TL the day after, while higher TL also led to lower TST the following night (P < .001). For the WC competitors, TST the night before the qualifications was shorter than the mean TST of the WC period (ES = −0.95, CI = −170:24, P = .030). TST correlated with coach ranking (r = −0.857, P = .014). Higher TL correlated with worse WC (r = 0.829, P = .042) and coach (r = 0.893, P = .007) ranking. This research in elite gymnasts indicated associations between decreased TST, augmented TL and inferior performance. Optimizing sleep and TL may therefore represent strategies to enhance performance.

Objective Sleep Characteristics of Young Elite Female Gymnasts: 420 Board #261 May 30 11

Objective sleep characteristics of young elite female gymnasts Dumortier J1, Boone J1, Mariman A2, Delesie L2, Tobback E2, Vogelaers D2, Bourgois JG1,2 1: Ghent University, Belgium; 2: Ghent University Hospital, Belgium Purpose Sleep is considered one of the most important recuperation techniques for elite athletes, with its specific features implicating different aspects of learning skills and physical recuperation. The aims of this study were (1) to assess objectively the sleep characteristics of elite gymnasts and (2) to correlate these findings with their age. Methods Twelve elite female gymnasts (15.1 ± 1.5 years old; VO2MAX: 53.18 ± 5.1 ml·min-1·kg-1; 30.7 ± 1.7 training hours/week) underwent a nocturnal polysomnography (PSG) after a regular training day (6 - 6.5 h of training). The PSG was scored according to the guidelines of the American Academy of Sleep Medicine (AASM). Time in bed (min), Total Sleep Time (TST, min), Sleep Efficiency (SE, %), Non Rapid Eye Movement 1 (NREM1, %), NREM2 (%), Slow Wave Sleep (SWS, %), REM (%), Wake After Sleep Onset (WASO, min), Sleep Onset Latency (SOL, min), Awakening Index (/h) and Apnea-Hypopnea-Index (/h) were measured and analyzed. Furthermore, the gymnasts completed the Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI). Sleep parameters were correlated with age using a Pearson Correlation. Results The following objective values were attained: time in bed 487 ± 13 min, TST 437 ± 27 min, SE 89.5 ± 4.1 %, NREM1 4.9 ± 3.6 %, NREM2 38.7 ± 10.2 %, SWS 36.9 ± 11.4 %, REM 19.3 ± 3.8 %, WASO 32.4 ± 9.2 min, SOL 18.3 ± 16.5 min, Awakening Index 16.1 ± 6.3 /h, Apnea-Hypopnea-Index 0.9 ± 0.8 /h, Epworth Sleepiness Scale 5.3 ± 2.5 (/24), PSQI 2.6 ± 1.9 (/21). Age-matched correlations for %SWS (R=-0.693, P=0.013) and arousals from SWS (R=-0.622, P=0.031) were found. The younger the gymnasts, the higher %SWS was found, with higher amounts of arousals from SWS in the younger gymnasts. Discussion Objective sleep assessments through PSG in elite female athletes suggest a higher amount of SWS compared to non-elite athletic peer students (Suppiah et al., Ped. Ex. Sc. 2016; 28: 588-595) as a salient feature in their sleep architecture. This may represent an advantage towards higher performance, as sleep deficits are related with lower performance. Hence, it needs to be explored whether a thorough analysis of elite athletes’ sleep should be incorporated in health screenings.

Tribute to Dr Jacques Rogge: muscle activity and fatigue during hiking in Olympic dinghy sailing

Abstract ‘A tribute to Dr J. Rogge’ aims to systematically review muscle activity and muscle fatigue during sustained submaximal quasi-isometric knee extension exercise (hiking) related to Olympic dinghy sailing as a tribute to Dr Rogge’s merits in the world of sports. Dr Jacques Rogge is not only the former President of the International Olympic Committee, he was also an orthopaedic surgeon and a keen sailor, competing at three Olympic Games. In 1972, in fulfilment of the requirements for the degree of Master in Sports Medicine, he was the first who studied a sailors’ muscle activity by means of invasive needle electromyography (EMG) during a specific sailing technique (hiking) on a self-constructed sailing ergometer. Hiking is a bilateral and multi-joint submaximal quasi-isometric movement which dinghy sailors use to optimize boat speed and to prevent the boat from capsizing. Large stresses are generated in the anterior muscles that cross the knee and hip joint, mainly employing the quadriceps at an intensity of 30–40% maximal voluntary contraction (MVC), sometimes exceeding 100% MVC. Better sailing level is partially determined by a lower rate of neuromuscular fatigue during hiking and for ≈60% predicted by a higher maximal isometric quadriceps strength. Although useful in exercise testing, prediction of hiking endurance capacity based on the changes in surface EMG in thigh and trunk muscles during a hiking maintenance task is not reliable. This could probably be explained by the varying exercise intensity and joint angles, and the great number of muscles and joints involved in hiking. Highlights Dr Jacques Rogge, former president of the International Olympic Committee and Olympic Finn sailor, was the first to study muscle activity during sailing using invasive needle EMG to obtain his Master degree in Sports Medicine at the Ghent University. Hiking is a critical bilateral and multi-joint movement during dinghy racing, accounting for >60% of the total upwind leg time. Hiking generates large stresses in the anterior muscles that cross the knee and hip joint. Hiking is considered as a quasi-isometric bilateral knee extension exercise. Muscle activity measurements during sailing, recorded by means of EMG, show a mean contraction intensity of 30-40% maximal voluntary contraction with peaks exceeding 100%. Hiking performance is strongly related to the development of neuromuscular fatigue in the quadriceps muscle. Since maximal strength is an important determinant of neuromuscular fatigue during hiking, combined strength and endurance training should be incorporated in the training program of dinghy sailors.