H MacLeod

The validity of a non-differential global positioning system for assessing player movement patterns in field hockey.

Abstract Nine games players (mean age 23.3 years, s = 2.8; height 1.73 m, s = 0.08; body mass 70.0 kg, s = 12.7) completed 14 laps of a measured circuit that incorporated intermittent running and directional changes, representative of the movements made by field hockey players during match-play. The distances and speeds recorded by a global positioning satellite (GPS) system (Spi Elite™) were compared statistically with speed measurements made using timing gates and distances measured using a calibrated trundle wheel, to establish the criterion validity of the GPS system. A validation of the speed of movement of each participant separately was also made, using data from each timing gate, over a range of speeds. The mean distance recorded by the GPS system was 6821 m (s = 7) and the mean speed was 7.0 km · h−1 (s = 1.9), compared with the actual distance of 6818 m and recorded mean speed of 7.0 km · h−1 (s = 1.9). Pearson correlations (r) among timing gate speed and GPS speed were ≥0.99 (P < 0.001) and the mean difference and 95% limits of agreement were 0.0 ± 0.9 km · h−1. These results suggest that a GPS system (Spi Elite™) offers a valid tool for measuring speed and distance during match-play, and can quickly provide the scientist, coach, and player with objective information about certain movement patterns during competitive games.

Time-motion analysis of elite women's field hockey, with particular reference to maximum intensity movement patterns

The aim of this study was to establish the activity profile of elite level female field hockey players during competition. In addition, the nature of sprint activity concerning pre- and post-sprint activity was investigated. Twelve elite female outfield players (age 22 ± 3 years) from the women’s English National League were videoed for the entire duration of a game. Definitions of each movement classification (stand, walk, jog, cruise, sprint) were established for analysis. A lunge defined as a sudden elongated step, but with a bent front knee, was included in analysis due to its frequent use in field hockey. The majority of the game was spent in low intensity activity (90%). A mean significant decrease (P<0.05) in the amount of high intensity activity performed in the second half, coupled with a significant decrease in average heart rate in the second half (174 ± 12 beats·min−1 vs. 169 ± 11 beats·min−1; p<0.01), suggests a manifestation of fatigue resulting in a decrease in physical performance. To conclude, field hockey is predominantly low intensity in nature, interspersed with short periods of high intensity effort. Despite the continuous substitutions rule, there is a decline in work rate in the second half.

Fluid balance and hydration habits of elite female field hockey players during consecutive international matches.

MacLeod, H and Sunderland, C. Fluid balance and hydration habits of elite female field hockey players during consecutive international matches. J Strength Cond Res 23(4): 1245-1251, 2009-The purpose of this study was to assess sweat loss and hydration practices of elite female field hockey players during consecutive international matches. Eighteen England U21 field hockey players were assessed during 2 consecutive international matches. Sweat loss was assessed from changes in body mass after correction for the volume of fluid consumed and any urine loss. Players completed a questionnaire to assess hydration habits and practices. Mean (± SD) change in body mass after match 1 was −0.1 ± 0.6 kg compared with −0.3 ± 0.5 kg after match 2. This equates to a percentage level of body mass change of −0.2 ± 1.1% after match 1 and −0.5 ± 0.7% after match 2. Mean fluid intake was 1264 ± 394 mL during match 1 and 1216 ± 488 mL during match 2. Prematch urine osmolality was significantly higher before match 2 (425 ± 206 mOsm·kg−1) compared with match 1 (197 ± 110 mOsm·kg−1; p = 0.008). There was no significant difference between morning body mass changes (p = 0.97); however, 14 players experienced reductions in body mass. There were large interindividual differences in sweat loss and drinking habits in players, ranging from levels of dehydration reaching 2% body mass loss to net body mass gains of 2.4%. Fluid loss was moderate, and players were aware of the impact that dehydration has on performance. With regular substitutions, moderate conditions, and a sound knowledge of correct hydration practice, hydration status was well maintained despite playing consecutive matches.

Previous-day hypohydration impairs skill performance in elite female field hockey players

The purpose of this study was to determine the effects of 2% hypohydration on skill performance in elite female field hockey players following intermittent exercise in the heat. Eight elite female field hockey players performed 50 min of a field hockey‐specific intermittent treadmill running protocol (FHITP) in hot environmental conditions (33 °C, 60% relative humidity) in different hydration states: euhydrated (EUH) and hypohydrated by 2% body mass (HYPO). Hydration status was manipulated via a period (121±10 min) of passive hyperthermia (40 °C, 75% relative humidity) and controlled fluid intake 1 day preceding testing. Ad libitum fluid intake was permitted throughout both trials. Field hockey skill tests were performed pre‐ and post‐FHITP. Skill performance time increased (P=0.029) in the HYPO trial compared with the EUH trial, which may be attributed to an increase in penalty time (P=0.024). Decision‐making time increased (P=0.008) in the HYPO trial and was significantly impaired compared with EUH (P=0.016) pre‐FHITP. Ad libitum drinking appeared to be sufficient to maintain decision‐making performance as no interaction effects were evident post‐FHITP. Players who commence match‐play in a state of hypohydration may be susceptible to decrements in skill and decision‐making performance.