Ceri Nicholas

The Loughborough Intermittent Shuttle Test: A field test that simulates the activity pattern of soccer

The aims of this study were to describe and determine the test-retest reliability of an exercise protocol, the Loughborough Intermittent Shuttle Test (the LIST), which was designed to simulate the activity pattern characteristic of the game of soccer. The protocol consisted of two parts: Part A comprised a fixed period of variable-intensity shuttle running over 20 m; Part B consisted of continuous running, alternating every 20 m between 55% and 95% VO 2max , until volitional fatigue. Seven trained games players (age 21.5 +/- 0.9 years, height 182 +/- 2 cm, body mass 80.1 +/- 3.6 kg, VO 2max 59.0 +/- 1.9 ml kg -1 min -1 ; mean s x ) performed the test on two occasions (Trial 1 and Trial 2), at least7 days apart, to determine the test-retest reliability of the sprint times and running capacity. The physiological and metabolic responses on both occasions were also monitored. The participants ingested water ad libitum during the first trial, and were then prescribed the same amount of water during the second trial. The 15 m sprint times during Trials 1 and 2 averaged 2.42 +/- 0.04 s and 2.43 +/- 0.04 s, respectively. Run time during Part B was 6.3 +/- 2.0 min for Trial 1 and 6.1 +/- 1.3 min for Trial 2. The 95% limits of agreement for sprint times and run times during Part B were -0.14 to 0.12 s and -3.19 to 2.16 min respectively. There were no differences between trials for heart rate, rating of perceived exertion, body mass change during exercise, or blood lactate and glucose concentrations during the test. Thus, we conclude that the sprint times and the Part B run times were reproducible within the limits previously stated. In addition, the activity pattern and the physiological and metabolic responses closely simulated the match demands of soccer.

Muscular soreness following prolonged intermittent high-intensity shuttle running

The aim of this study was to examine the impact of prolonged intermittent high-intensity shuttle running on soreness and markers of muscle damage. Sixteen males took part in the study, half of whom were assigned to a running group and half to a resting control group. The exercise protocol involved 90 min of intermittent shuttle running and walking (Loughborough Intermittent Shuttle Test: LIST), reflecting the activity pattern found in multiple-sprint sports such as soccer. Immediately after exercise, there was a significant increase (P < 0.05) in serum activities of creatine kinase and aspartate aminotransferase, and values remained above baseline for 48 h (P < 0.05). Median peak activities of creatine kinase and aspartate aminotransferase occurred 24 h post-exercise and were 774 and 43 U x l(-1), respectively. The intensity of general muscle soreness, and in the specific muscles investigated, was greater than baseline for 72 h after the shuttle test (P < 0.05), peaking 24-48 h post-exercise (P < 0.05). Muscle soreness was not correlated with either creatine kinase or aspartate aminotransferase activity. Soreness was most frequently reported in the hamstrings. Neither soreness nor serum enzyme activity changed in the controls over the 4 day observation period. It appears that unaccustomed performance of prolonged intermittent shuttle running produces a significant increase in both soreness and markers of muscle damage.

The Effect of Intermittent High-Intensity Running on Gastric Emptying of Fluids in Man

PURPOSE This study examined the effect of variable-intensity shuttle running on gastric emptying of a carbohydrate-free placebo (Plac) drink and of a 6.4% carbohydrate-electrolyte (CHO) sports drink. METHOD We compared the volume of test drink emptied during two 15-min periods of walking exercise (WE) with that during two 15-min periods of the Loughborough Intermittent Shuttle Test (LIST). Gastric emptying was measured on the four trials using a double-sampling aspiration technique in eight healthy males after ingestion of a 420 +/- 49 mL and a 168 +/- 20 mL bolus of the appropriate test drink at the start of the first and second exercise period, respectively. RESULTS During the initial 15 min of exercise, the mean (+/-SD) volume of Plac (124 +/- 95 mL) and CHO (71 +/- 43 mL) drink emptied was similar between the two LIST trials, but the volume of Plac (227 +/- 85 mL) and CHO (159 +/- 63 mL) drinks emptied on the WE trials was greater than for the respective test drinks on the LIST trials. Similar volumes of test drinks were emptied on all trials (P = 0.20) during the second 15 min of exercise. Over the 30 min of each trial, the exercise intensity of the LIST reduced the volume of the Plac (211 +/- 108 mL) and CHO (208 +/- 83 mL) drink emptied compared with that on the WE trial for the Plac (396 +/- 74 mL) and CHO (293 +/- 73 mL) drink, respectively. CONCLUSIONS The exercise intensity of the LIST is sufficient to slow gastric emptying of carbohydrate and noncarbohydrate containing drinks compared with walking. Dilute carbohydrate-electrolyte drinks empty at about the same rate as carbohydrate-free beverages during variable-intensity running.

Semi-automated time-motion analysis of senior elite rugby league

The aim of this study was to examine the movement demands of senior elite rugby league with consideration of the impact of player position and match phase. A semi-automated match analysis image recognition system (ProZone 3, ProZone®, Leeds, England) was used to track 78 players during three senior elite matches. Players were categorised as outside backs (n = 30), pivots (n = 18), props (n = 12) or back row (n = 18). Total Distance (TD) covered, work-to-rest ratio (WRR) and % total time (%TT) spent in each of seven selected locomotive categories were determined for defending, attacking, ball in play and ball out of play phases. Analysis revealed that during the 86.8 min of match time, the mean TD covered was 8,503 ± 631 m, with pivots (8,800 ± 581 m) and outside backs (8,142 ± 630 m) covering the most and least distances, respectively. For pivots, props and back row players, defending resulted in a significantly lower WRR than when attacking (P < 0.05). Outside backs had significantly higher WRRs for ball in play and defending than all other positional groups (P < 0.05). The time-motion data presented in this study provides position-specific benchmarks for assessing match performance.

HEART RATE RESPONSES TO SMALL-SIDED GAMES AMONG ELITE JUNIOR RUGBY LEAGUE PLAYERS

Foster, CD, Twist, C, Lamb, KL, and Nicholas, CW. Heart rate responses to small-sided games among elite junior rugby league players. J Strength Cond Res 24(4): 906-911, 2010-This study investigated the influences of player number and playing area size on the heart rate (HR) responses elicited by junior male rugby league players during small-sided games (SSGs). Twenty-two players from a professional club (n = 22, mean age: 14.5 ± 1.5 years; stature: 172.5 ± 11.4 cm; body mass: 67.8 ± 15.1 kg; &OV0312;o2peak: 53.3 ± 5.6 mL·kg−1·min−1; HRmax: 198 ± 7.8 beats·min−1) participated in 2 repeated trials of six 4-minute conditioned SSGs over a 2-week period. The SSGs varied by playing area size-15 × 25 m, 20 × 30 m, and 25 × 35 m-and player number-4v4 and 6v6. HRs were recorded continuously in each game and expressed as overall and age-related (15-16 and 12-13 years) means and percent of maximum (%HRmax). Analysis revealed nonsignificant (p > 0.05) effects of trials and playing area size on HRs but a significant effect of player number in the 15-16 age group only (p < 0.001), with HRs being higher in the 4v4 (90.6% HRmax) than the 6v6 SSGs (86.2% HRmax). The HR responses were found to be repeatable in all SSG conditions (within ± 1.9% HRmax), apart from the small 6v6 condition in the older players. The findings demonstrate that these SSGs generate physiological responses suitable for aerobic conditioning that, although unaffected by the size of the area used, are sensitive to the player number. Accordingly, among such players it is advisable that coaches use 4v4 SSGs to achieve an appropriate and consistent aerobic conditioning stimulus.

The reliability and validity of short-distance sprint performance assessed on a nonmotorized treadmill

Highton, JM, Lamb, KL, Twist, C, and Nicholas, C. The reliability and validity of short-distance sprint performance assessed on a nonmotorized treadmill. J Strength Cond Res 26(2): 458–465, 2012—This study examined the interday and intraday reliabilities and validities of various sprint performance variables on a nonmotorized treadmill (NMT) over distances of 10, 20, and 30 m. After habituation, 12 male team-sport players performed 3 sprints on the NMT on 2 separate days and an assessment of overground running performance, separated by 24 hours. Measurements included sprint times, mean and peak sprint speeds, and step length and frequency. Data analysis revealed no significant mean differences (p > 0.05) between NMT variables recorded on the same day or between days. Ratio limits of agreement indicated that the best levels of agreement were in 20-m (1.02 ×/÷ 1.09) and 30-m (1.02 ×/÷ 1.07) sprint times, peak (1.00 ×/÷ 1.06) and mean (0.99 ×/÷ 1.07) running speed, and step length (0.99 ×/÷ 1.09) and frequency (1.01 ×/÷ 1.06). The poorest agreement was observed for time to peak running speed (1.10 ×/÷ 1.47). These reliability statements were reinforced by coefficients of variation being <5% for all the variables except time to peak running speed (11%). Significant differences (p < 0.05) were observed between NMT and overground sprint times across all distances, with times being lower (faster) by approximately 25–30% overground. The correlations between NMT and overground variables were generally modest (0.44–0.67), and optimal for time to cover 30 m on day 2. Our data support NMT ergometry as a reliable tool for most of the sprint performance variables measured and reveal that the fastest 30-m overground sprinters were likely to be identifiable via NMT ergometry.

The development of a reliable amateur boxing performance analysis template

Abstract The aim of this study was to devise a valid performance analysis system for the assessment of the movement characteristics associated with competitive amateur boxing and assess its reliability using analysts of varying experience of the sport and performance analysis. Key performance indicators to characterise the demands of an amateur contest (offensive, defensive and feinting) were developed and notated using a computerised notational analysis system. Data were subjected to intra- and inter-observer reliability assessment using median sign tests and calculating the proportion of agreement within predetermined limits of error. For all performance indicators, intra-observer reliability revealed non-significant differences between observations (P > 0.05) and high agreement was established (80–100%) regardless of whether exact or the reference value of ±1 was applied. Inter-observer reliability was less impressive for both analysts (amateur boxer and experienced analyst), with the proportion of agreement ranging from 33–100%. Nonetheless, there was no systematic bias between observations for any indicator (P > 0.05), and the proportion of agreement within the reference range (±1) was 100%. A reliable performance analysis template has been developed for the assessment of amateur boxing performance and is available for use by researchers, coaches and athletes to classify and quantify the movement characteristics of amateur boxing.

Carbohydrate-protein coingestion improves multiple-sprint running performance

Abstract Acute carbohydrate-protein ingestion has been shown to improve steady-state endurance performance. This study compared the effects of carbohydrate and carbohydrate-protein ingestion on self-regulated simulated multiple-sprint sport performance. Nine participants completed two trials of a modified Loughborough Intermittent Shuttle Test involving 4 x 15 min blocks of regulated exercise followed by 2 x 15 min blocks of self-regulated exercise. Participants consumed 2.5 ml · kg−1 of an 8% carbohydrate (CHO trial) or 6% carbohydrate plus 2% whey protein beverage (CHO-P trial) every 15 minutes. Distance covered (4.2%) and maximal speed (6.1%) decreased (P < 0.05) in the final 15 min of exercise, and whilst not significant, carbohydrate-protein elicited a very likely moderate (2.5: 90% confidence limits; ±1.4%) and possibly small (1.9: ±3.3%) improvement in each variable, respectively. Average running speed declined in the final 15 min of the CHO trial only (P = 0.002), with protein providing a likely small improvement (2.7%: ±2.5%). No differences (P > 0.05) between beverages were observed in body mass or plasma volume change, urine volume, heart rate, gut fullness, rating of perceived exertion (RPE), blood glucose or serum insulin. Blood urea concentration increased in the CHO-P trial only (mean ± SD: 45.4 ± 9.9 c.f. 39.2 ± 11.4 g · dL−1, P = 0.003). These findings show carbohydrate-protein ingestion is likely to enhance multiple-sprint sport exercise performance above carbohydrate, potentially through altered central fatigue or increased protein oxidation.

An evaluation of the external validity and reliability of a rugby league match simulation protocol

Abstract The aim of this study was to assess the external validity and reliability of a novel rugby league match simulation protocol. With ethical approval, 16 males (age 22.4 ± 7.1 years, estimated 52.1 ± 4.5 ml · kg−1 · min−1) performed the rugby league match simulation protocol on two occasions 10 to 14 days apart. During the rugby league match simulation protocol participants covered a total distance of 8,444 ± 212 m, at an overall locomotive rate of 97.3 ± 2.5 m · min−1. In addition, changes in very high (−22.4%), high (−8.6%) and low intensity (1.6%) running locomotive rates from the first to the fourth quarter were observed. The magnitude of these movement characteristics did not differ significantly (P > 0.05) between repeated trials, with coefficients of variation of 1.1, 4.2 and 10.6%, and 95% limits of agreement of −0.4 ± 4.0, −0.3 ± 3.6, and −0.2 ± 4.4 m · min−1 for overall, high and very high intensity running locomotive rates, respectively. On this evidence, the rugby league match simulation protocol replicates the movement demands observed during elite rugby league matches. Furthermore, the protocol can be performed reliably amongst non-elite sports players and thereby has the potential to be used as a tool for monitoring the effectiveness of various interventions on physical match performance.

Effects of exercise-induced muscle damage on resting metabolic rate, sub-maximal running and post-exercise oxygen consumption

Abstract Exercise-induced muscle damage (EIMD), described as the acute weakness of the musculature after unaccustomed eccentric exercise, increases oxidative metabolism at rest and during endurance exercise. However, it is not known whether oxygen uptake during recovery from endurance exercise is increased when experiencing symptoms of EIMD. Therefore, the purpose of this study was to investigate the effects of EIMD on physiological and metabolic responses before, during and after sub-maximal running. After a 12 h fast, eight healthy male participants completed baseline measurements comprising resting metabolic rate (RMR), indirect markers of EIMD, 10 min of sub-maximal running and 30 min of recovery to ascertain excess post-exercise oxygen consumption (EPOC). Measurements were then repeated at 24 and 48 h after 100 Smith-machine squats. Data analysis revealed significant (P<0.05) increases in muscle soreness and creatine kinase (CK) and decreases in peak knee extensor torque at 24 and 48 h after squatting exercise. Moreover, RMR, physiological, metabolic and perceptual responses during sub-maximal running and EPOC were increased in the two days after squatting exercise (P<0.05). It is suggested that the elevated RMR was a consequence of a raised energy requirement for the degradation and resynthesis of damaged muscle fibres. The increased oxygen demand during sub-maximal running after muscle damage was responsible for the increase in EPOC. Individuals engaging in unaccustomed resistance exercise that results in muscle damage should be mindful of the increases in resting energy expenditure and increased metabolic demand to exercise in the days that follow.