The validity of raw custom-processed global navigation satellite systems data during straight-line sprinting across multiple days.

OBJECTIVES: (1) Determine the validity of instantaneous speed and acceleration and (2) the variation in validity over time (multiple sessions) for global navigation satellite systems (GNSS) devices. DESIGN: Repeated measures. METHODS: 10-Hz GNSS devices from Statsports (n = 2, Apex Pro) and Catapult (n = 2, Vector S7) were examined, whilst a speed laser manufactured by MuscleLab (n = 1, LaserSpeed) was the criterion measure, sampling at 2.56 kHz, with data exported at 1000 Hz. Ten participants completed 40 m sprinting and changes of pace on three separate days. Root mean square error (RMSE) was used to assess the magnitude and direction of the difference between GNSS and criterion measures (instantaneous speed, instantaneous acceleration). Linear mixed models were built to assess the difference in validity across days. RESULTS: RMSE ranged from 0.14 to 0.21 m·s-1 and 0.22 to 0.47 m·s-2 for speed and acceleration, respectively showing strong agreement. There were small variations in the agreement to criterion between days for both devices for speed (Catapult RMSE = 0.12 to 21 m·s-1; Statsports RMSE = 0.14 to 0.17 m·s-1) and for acceleration (Catapult RMSE = 0.26 to 0.47 m·s-2; Statsports RMSE = 0.22 to 0.43 m·s-2) across all movements. There was a negative linear relationship between speed and acceleration error as speed increased. CONCLUSIONS: Wearable microtechnology devices from Catapult (Vector S7) and Statsports (Apex Pro) have suitable validity when measuring instantaneous speed and acceleration across multiple days. There may be small variations during different sessions and over the speed spectrum.

Relationship Between Preseason Training Load, Match Performance, and Match Activities in Professional Rugby League.

ABSTRACT: Crang, ZL, Hewitt, A, Scott, TJ, Kelly, VG, and Johnston, RD. Relationship between pre-season training load, match performance and match activities in professional rugby league. J Strength Cond Res 36(9): 2581-2588, 2022-This study aimed to establish the relationship between preseason training loads, technical match performance, and physical match activities in rugby league. Twenty-two professional rugby league players (age: 24.7 ± 4.0 years; height: 184.3 ± 4.7 cm; and body mass: 101.1 ± 9.9 kg) participated in the study. Training loads and physical match activities were monitored using global positioning systems. Total distance (m), high-speed running distance (VT 1IFT ; distance covered above estimated first ventilatory threshold [≥68% of 30-15 intermittent fitness test]) and total session rating of perceived exertion from all field-based (32.5 ± 8.5) and gym-based sessions (39.1 ± 12.5) were used to quantify preseason loads. Physical match activities were measured as total and high-speed running distance relative to individual playing time, whereas technical match activities and performance scores were used to evaluate individual match performance. To examine the relationship between physical match activities, technical performance, and preseason load, Pearson's correlation coefficients were quantified for each in-season game before performing a Fisher Z Transformation. Preseason high-speed running distance was positively associated with high-speed match activities ( r = 0.34-0.51), whereas negatively associated with technical performance scores ( r = -0.51 to -0.35) and hit up m·min -1 of match-play ( r = -0.30 to -0.17). It seems high speed running performed in the preseason period positively influences in-season physical match activity profiles, however, are unlikely to positively impact technical match performance.

The inter-device reliability of global navigation satellite systems during team sport movement across multiple days.

OBJECTIVES: (1) Determine the inter-device and inter-manufacturer reliability; and (2) investigate the variation in reliability over time for common global navigation satellite systems. DESIGN: Repeated measures. METHODS: A total of twenty 10-Hz devices manufactured by StatSports (n = 10, Apex Pro; StatSports, Newry, Ireland) and Catapult Sports (n = 10, Vector S7; Catapult Sports, Melbourne, Australia) were towed on a sprint sled during 8 × 40-minute team sport movement protocol over a 4-week period. The coefficient of variations for distance, velocity and acceleration/deceleration metrics were calculated to show dispersion of the data relative to the mean or median for each manufacturer and interpreted as good, ≤5%; moderate, <10%; and poor, coefficient of variation ≥10%. The coefficient of variation range described the variation in reliability and was interpreted as small, ≤5%; moderate, <10% and large, ≥10%. Inter-manufacturer agreement was represented as a Cohen d (±95% confidence interval) standardised effect size. RESULTS: Inter-device reliability for distance, peak velocity and average acceleration was good (coefficient of variation = 0.1 to 3.9%) for both manufacturers, with small variation across sessions. For most threshold-based acceleration and deceleration counts, StatSports devices showed good to moderate reliability, with moderate variation across sessions; Catapult showed good to poor reliability, with large variation across sessions. Inter-manufacturer agreement demonstrated moderate to very large effect sizes reported for most metrics. CONCLUSIONS: Reliability was suitable and consistent for measures of distance, velocity, and average acceleration. StatSports devices generally possessed suitable reliability and consistency for threshold-based accelerations and decelerations, though Catapult devices did not. Most metrics should not be compared between manufacturers.

The Validity and Reliability of Wearable Microtechnology for Intermittent Team Sports: A Systematic Review.

BACKGROUND: Technology has long been used to track player movements in team sports, with initial tracking via manual coding of video footage. Since then, wearable microtechnology in the form of global and local positioning systems has provided a less labour-intensive way of monitoring movements. As such, there has been a proliferation in research pertaining to these devices. OBJECTIVE: A systematic review of studies that investigate the validity and/or reliability of wearable microtechnology to quantify movement and specific actions common to intermittent team sports. METHODS: A systematic search of CINAHL, MEDLINE, and SPORTDiscus was performed; studies included must have been (1) original research investigations; (2) full-text articles written in English; (3) published in a peer-reviewed academic journal; and (4) assessed the validity and/or reliability of wearable microtechnology to quantify movements or specific actions common to intermittent team sports. RESULTS: A total of 384 studies were retrieved and 187 were duplicates. The titles and abstracts of 197 studies were screened and the full texts of 88 manuscripts were assessed. A total of 62 studies met the inclusion criteria. Additional 10 studies, identified via reference list assessment, were included. Therefore, a total of 72 studies were included in this review. CONCLUSION: There are many studies investigating the validity and reliability of wearable microtechnology to track movement and detect sport-specific actions. It is evident that for the majority of metrics, validity and reliability are multi-factorial, in that it is dependent upon a wide variety of factors including wearable technology brand and model, sampling rate, type of movement performed (e.g., straight line, change of direction) and intensity of movement (e.g., walk, sprint). Practitioners should be mindful of the accuracy and repeatability of the devices they are using when making decisions on player training loads.