ECSS Paris 2023: CP-AP01
INTRODUCTION: The importance of athlete monitoring in team sports is now widely recognised and commonly achieved using GNSS trunk-mounted player tracking systems. Systems allow for the output and interpretation of multiple external load metrics which practitioners use to inform the prescription and adaptation of training load. However, interunit reliability is important to allow comparisons to be made within and between athletes and teams. The aim of this study was to assess the interunit reliability of STATSports Apex units during repeated sprints of varied distances and changes of direction, to assess how reliability and metrics may change with the demands of repeated sprints. METHODS: Thirty-three female football players performed 5 sets of 2 x 20 m, 4 x 10m and 8 x 5 m repeated sprint protocols (200m total), while wearing two harnesses and STATSports Apex GNSS units, placed alongside each other, between the scapulae. The interunit reliability was assessed using intraclass correlation coefficient (ICC), for each protocol and all combined, for a selection of GNSS and accelerometer-based (ACC) metrics. One-way ANOVAs were used to compare the metrics reported for each sprint protocol. RESULTS: Across all protocols GNSS metrics demonstrated good to excellent interunit reliability (ICC: 0.845 - 0.999), while ACC metrics fatigue index (ICC: 0.495) and dynamic stress load (ICC: 0.484) were poor. Variation in reliability across individual sprint protocols was found for accelerations (2 x 20m ICC: 0.692, moderate; 4 x 10m ICC: 0.865, good; 8 x 5m ICC: 0.789, good), metabolic distance (2 x 20m ICC: 0.871, good; 4 x 10m ICC: 0.928, excellent; 8 x 5m ICC: 0.974, excellent), fatigue index (2 x 20m ICC: 0.393, poor; 4 x 10m ICC: 0.438, poor; 8 x 5m ICC: 0.544, moderate), and dynamic stress load (2 x 20m ICC: 0.445, poor; 4 x 10m ICC: 0.455, poor; 8 x 5m ICC: 0.539, moderate). Notably, despite increased acceleration and deceleration demands with more changes of direction, ACC metrics were not significantly different between any sprint protocols (p = 0.064 - 1.000). CONCLUSION: GNSS metrics show good to excellent interunit reliability, except for accelerations (moderate to good), therefore it is recommended that practitioners can confidently use APEX GNSS units for load monitoring of GNSS metrics. However, ACC metrics have demonstrated largely poor to moderate interunit reliability and highlighted difficulty distinguishing between the demands of varied sprint distances. It has been recognised that the ICC increases from 2 x 20m to 8 x 5m, suggesting that reliability may improve by increasing the amount of activity monitored. Therefore, short protocol duration may also explain the lack of significant differences identified between sprint protocols. It is recommended to avoid the interchanging of units between athletes and sessions, and interpret ACC metrics cautiously, with regard to the type and duration of activity being monitored.
Read CV Laura DawsonECSS Paris 2023: CP-AP01
INTRODUCTION: Studies on respiratory patterns in tennis are rare and there is no evidence regarding the relation between stroke production, breathing patterns and oxygen uptake. Therefore, the aim of this study was to compare respiratory patterns and gas exchange during a standardized tennis protocol with corresponding measures during continuous treadmill running at a similar oxygen uptake. METHODS: 15 female and male competitive tennis players (women n= 7: age: 22.6 ± 2.4 years, weight: 69.7 ± 11.9 kg, height: 172.6 ± 8.0 cm; men n= 8: age: 25.5 ± 3.1 years, weight: 83.4 ± 8.2 kg, height: 187.4 ± 6.8 cm) completed three experimental parts on separate occasions. A standardized tennis protocol (TP, Day 1), a treadmill-based incremental running test (RT, Day 2) and a standardized running protocol metabolically matched to TP (RP, Day 3). TP (Day 1) included low or high running loads (RL, RH) and low or high stroke velocities (SL, SH) which were combined in four stages (TP1: RL+SL; TP2: RL+SH; TP3: RH+SL; TP4: RH+SH). RT (Day 2) was used to determine the running velocity matching the oxygen consumption during each stage of TP (TP1-TP4). RP (Day 3) included four stages with identical length and oxygen consumption as during TP. Oxygen uptake (VO2), energy expenditure (EE), tidal volume (VT), breathing frequency (bf), minute ventilation (V’E), inspiration (tI) and expiration time (tE) as well as stroke velocity (SV) were compared between TP and RP. Number (NP) and duration of breathing Plateaus (DP) were calculated from VT. A plateau was defined as a minimum of 0.2 s with no air exchange and constant VT. TP was recorded by video and synchronized to respiratory data. Repeated measures ANOVA was used to compare TP and RP on each stage. RESULTS: Mean VO2 (p<.001), EE (p<.001), and RER (p<.001) increased significantly between stage 1 to 4 but did not differ between TP and RP. TP corresponded to mean running velocities of 3.2±0.2 m/s (RP1), 3.5±0.4 m/s (RP2), 3.8±0.5 m/s (RP3) and 4.2±0.5 m/s (RP4). Regarding respiration parameters, NP was significantly higher in TP compared to RP on stages TP2 (5.9±3.8vs.0.4±0.5,p<.001), TP3 (2.6±2.7vs.0.3±0.6,p=0.04) and TP4 (4.6±4.1vs.0.3±0.6,p<.001). No significant differences were observed for VT, bf, V’E, tI and tE between TP and RP. Specifically in tennis, VT (1.8±0.4 vs. 2.9±0.7 L/s,p<.001), bf (36.2±7.7vs.44.3±6.6 b.min-1,p<.001) and V’E (52.9±11.3vs.85.0±18.4L/min,p<.001) increased from TP1 to TP4, whereas tI (0.9±0.2vs.0.8±0.1s,p<.001) and tE (0.9±0.2vs.0.7±0.1s,p<.001) decreased. NP was higher in TP2 (p<.001) compared to TP1, whereas no differences were found between TP3 and TP4 and DP. CONCLUSION: Respiration patterns differ significantly between tennis and running. Breathing plateaus occur exclusively in tennis during a time window around the hitting point and can be attributed to a higher hitting power. These specific demands might come along with challenges for coaches since powerful strokes can be accompanied with individual respiratory disturbances.
Read CV Katharina RaaschECSS Paris 2023: CP-AP01
INTRODUCTION: Football players are required to perform intermittent and multi-directional high-intensity accelerations and decelerations (HIAD), which impacts the players performance (1). Among various technologies to assess HIAD in football (2-3), Global Positioning System (GPS) devices and Inertial Measurements Units (IMU) embedded into GPS are often used to monitor the football players’ activities. The present systematic literature review aims to investigate the validity, reliability and responsiveness of HIAD metrics commonly used in football. METHODS: A systematic search of scientific articles published from January 1990 to March 2023 was conducted in three databases (PubMed, Web of Science and SPORTDiscus). Inclusion criteria were: full text in English; inclusion of information regarding the validity, reliability, and responsiveness of GPS and IMU of HIAD metrics. The study selection was performed by two independent authors assessing titles, abstracts and full text. The methodological quality of eligible studies was performed using the COSMIN checklist, therefore each study was rated on a 4-point scale: “very good”, “adequate”, “doubtful”, “inadequate”, and the lowest rating per measurement property was consider as quality outcome (4). RESULTS: Out of a preliminary list of 152 studies, 15 papers met the inclusion criteria and an additional 7 studies were identified through a snowballing technique, resulting in a total of 22 studies. Findings revealed 8 studies examining validity (construct validity: n=2; criterion validity: n=6). The construct validity studies focused on IMU metrics (i.e. player load) and showed a lack of gold standards, despite their “very good” methodological quality. Radar guns, timing gates and portable gas analyzer were used to validate peak acceleration/deceleration and metabolic power metrics in the criterion validity studies, with five showing “very good” methodological quality and one “doubtful”. Reliability was investigated in 17 studies with 2 rated as “adequate”, 13 as “doubtful”, and 2 as “inadequate” in methodological quality. The unclear stability of the participants, the time interval, and the conditions during the test and re-test procedures, negatively affected the methodological quality of the “inadequate” studies. Finally, no studies investigated the metrics’ responsiveness. CONCLUSION: The present systematic review generally highlights inconsistent methodological quality for both validity and reliability studies, which should caution sport scientists and football coaches in interpreting the collected HIAD metrics when monitoring daily practice. Therefore, further investigations are warranted to provide thorough validity, reliability and responsiveness of HIAD metrics in football. REFERENCES: 1) Bangsbo J. Acta Physiol Scand Suppl 1994 2) Delaney JA, J Strength Cond Res. 2018 3) Harper DJ, Sports Med, 2019 4) Mokkink LB, Qual Life Res. 2018
Read CV Christian Di ClaudioECSS Paris 2023: CP-AP01