Anthony P. Turner

Acute, intermediate intensity exercise, and speed and accuracy in working memory tasks: A meta-analytical comparison of effects

The purpose of this study was to compare, using meta-analytic techniques, the effect of acute, intermediate intensity exercise on the speed and accuracy of performance of working memory tasks. It was hypothesized that acute, intermediate intensity exercise would have a significant beneficial effect on response time and that effect sizes for response time and accuracy data would differ significantly. Random-effects meta-analysis showed a significant, beneficial effect size for response time, g=-1.41 (p<0.001) but a significant detrimental effect size, g=0.40 (p<0.01), for accuracy. There was a significant difference between effect sizes (Z(diff)=3.85, p<0.001). It was concluded that acute, intermediate intensity exercise has a strong beneficial effect on speed of response in working memory tasks but a low to moderate, detrimental one on accuracy. There was no support for a speed-accuracy trade-off. It was argued that exercise-induced increases in brain concentrations of catecholamines result in faster processing but increases in neural noise may negatively affect accuracy.

Carbohydrate Ingestion during Team Games Exercise: Current Knowledge and Areas for Future Investigation

There is a growing body of research on the influence of ingesting carbohydrate-electrolyte solutions immediately prior to and during prolonged intermittent, high-intensity exercise (team games exercise) designed to replicate field-based team games. This review presents the current body of knowledge in this area, and identifies avenues of further research. Almost all early work supported the ingestion of carbohydrate-electrolyte solutions during prolonged intermittent exercise, but was subject to methodological limitations. A key concern was the use of exercise protocols characterized by prolonged periods at the same exercise intensity, the lack of maximal- or high-intensity work components and long periods of seated recovery, which failed to replicate the activity pattern or physiological demand of team games exercise. The advent of protocols specifically designed to replicate the demands of field-based team games enabled a more externally valid assessment of the influence of carbohydrate ingestion during this form of exercise. Once again, the research overwhelmingly supports carbohydrate ingestion immediately prior to and during team games exercise for improving time to exhaustion during intermittent running.While the external validity of exhaustive exercise at fixed prescribed intensities as an assessment of exercise capacity during team games may appear questionable, these assessments should perhaps not be viewed as exhaustive exercise tests per se, but as indicators of the ability to maintain high-intensity exercise, which is a recognized marker of performance and fatigue during field-based team games. Possible mechanisms of exercise capacity enhancement include sparing of muscle glycogen, glycogen resynthesis during low-intensity exercise periods and attenuated effort perception during exercise. Most research fails to show improvements in sprint performance during team games exercise with carbohydrate ingestion, perhaps due to the lack of influence of carbohydrate on sprint performance when endogenous muscle glycogen concentration remains above a critical threshold of ∼200 mmol/kg dry weight. Despite the increasing number of publications in this area, few studies have attempted to drive the research base forward by investigating potential modulators of carbohydrate efficacy during team games exercise, preventing the formulation of optimal carbohydrate intake guidelines. Potential modulators may be different from those during prolonged steady-state exercise due to the constantly changing exercise intensity and frequency, duration and intensity of rest intervals, potential for team games exercise to slow the rate of gastric emptying and the restricted access to carbohydrate-electrolyte solutions during many team games.This review highlights fluid volume, carbohydrate concentration, carbohydrate composition and solution osmolality; the glycaemic index of preexercise meals; fluid and carbohydrate ingestion patterns; fluid temperature; carbohydrate mouthwashes; carbohydrate supplementation in different ambient temperatures; and investigation of all of these areas in different subject populations as important avenues for future research to enable a more comprehensive understanding of carbohydrate ingestion during team games exercise.

Postactivation potentiation of sprint acceleration performance using plyometric exercise.

Abstract Turner, AP, Bellhouse, S, Kilduff, LP, and Russell, M. Postactivation potentiation of sprint acceleration performance using plyometric exercise. J Strength Cond Res 29(2): 343–350, 2015—Postactivation potentiation (PAP), an acute and temporary enhancement of muscular performance resulting from previous muscular contraction, commonly occurs after heavy resistance exercise. However, this method of inducing PAP has limited application to the precompetition practices (e.g., warm-up) of many athletes. Very few studies have examined the influence of plyometric activity on subsequent performance; therefore, we aimed to examine the influence of alternate-leg bounding on sprint acceleration performance. In a randomized crossover manner, plyometric-trained men (n = 23) performed seven 20-m sprints (with 10-m splits) at baseline, ∼15 seconds, 2, 4, 8, 12, and 16 minutes after a walking control (C) or 3 sets of 10 repetitions of alternate-leg bounding using body mass (plyometric, P) and body mass plus 10% (weighted plyometric, WP). Mean sprint velocities over 10 and 20 m were similar between trials at baseline. At ∼15 seconds, WP impaired 20-m sprint velocity by 1.4 ± 2.5% when compared with C (p = 0.039). Thereafter, 10- and 20-m sprint velocities improved in WP at 4 minutes (10 m: 2.2 ± 3.1%, p = 0.009; 20 m: 2.3 ± 2.6%, p = 0.001) and 8 minutes (10 m: 2.9 ± 3.6%, p = 0.002; 20 m: 2.6 ± 2.8%, p = 0.001) compared with C. Improved 10-m sprint acceleration performance occurred in P at 4 minutes (1.8 ± 3.3%, p = 0.047) relative to C. Therefore, sprint acceleration performance is enhanced after plyometric exercise providing adequate recovery is given between these activities; however, the effects may differ according to whether additional load is applied. This finding presents a practical method to enhance the precompetition practices of athletes.

Beyond the Catecholamines Hypothesis for an Acute Exercise–Cognition Interaction: A Neurochemical Perspective

Abstract Research shows that moderate duration, moderate intensity, acute exercise generates increases in plasma catecholamines concentrations, which stimulate the vagal/nucleus tractus solitarii pathway. This induces the synthesis and release of catecholamines in the brain. Moderate increases in catecholamines concentrations facilitate performance of most cognitive tasks. Long duration, moderate intensity, and heavy exercise generate excessive concentrations of catecholamines, as well as resulting in increased concentrations of cortisol, which interact with catecholamines to inhibit working memory. However, heavy exercise has a beneficial effect on long-term memory due to activation of β-adrenoreceptors in the hippocampus and increased exercise-induced brain-derived neurotrophic factor (BDNF) levels, which aid neurogenesis and neuroplasticity. Heavy exercise also facilitates performance of autonomous tasks, probably due to activation of α1- and β-adrenoreceptors. With attention/perception tasks results are somewhat equivocal, although theoretically activation of α1- and β-adrenoreceptors should also aid the performance of these tasks.

The Acute Effect of Different Frequencies of Whole-Body Vibration on Countermovement Jump Performance

Turner, AP, Sanderson, MF, and Attwood, LA. The acute effect of different frequencies of whole body vibration on countermovement jump performance. J Strength Cond Res 25(6): 1592-1597, 2011—Whole-body vibration (WBV) has been shown to elicit acute and chronic improvements in neuromuscular function; however, there is little conclusive evidence regarding an optimum protocol for acute WBV. The aim of this study was to compare the effects of acute exposure to different frequencies of WBV on countermovement jump (CMJ) height. Twelve recreationally trained men (age, 31 ± 8 years; height, 177 ± 12 cm; weight, 83.0 ± 6.9 kg) completed maximal CMJs pre- and post-WBV in a half-squat position for 30 seconds. In a blinded design with randomized testing order, participants were exposed on different days to frequencies of 0, 30, 35, and 40 Hz. Significant main effects were found for time (pre-to-post WBV, p < 0.01) and frequency * time interaction (p < 0.01), with post hoc analysis highlighting that there was a significant mean improvement of 6% in CMJ as a result of WBV at 40 Hz but no significant change at other frequencies. This study demonstrates that for recreationally trained men, an acute 30-second bout of vertical WBV at 40 Hz and 8-mm peak-to-peak displacement significantly enhances explosive jumping performance in comparison to other frequencies. Acute vertical WBV for 30 seconds at 40 Hz may be incorporated into strength and conditioning training to enhance explosive power; however, the exact mechanisms for improvements remain to be elucidated and further well-controlled investigations on chronic WBV training and using well-trained athletes are recommended.

Influence of caffeine on perception of effort, metabolism and exercise performance following a high-fat meal

Abstract This study examined the effects of caffeine, co-ingested with a high fat meal, on perceptual and metabolic responses during incremental (Experiment 1) and endurance (Experiment 2) exercise performance. Trained participants performed three constant-load cycling tests at approximately 73% of maximal oxygen uptake ([Vdot]O2max) for 30 min at 20°C (Experiment 1, n = 8) and to the limit of tolerance at 10°C (Experiment 2, n = 10). The 30 min constant-load exercise in Experiment 1 was followed by incremental exercise (15 W · min−1) to fatigue. Four hours before the first test, the participants consumed a 90% carbohydrate meal (control trial); in the remaining two tests, the participants consumed a 90% fat meal with (fat + caffeine trial) and without (fat-only trial) caffeine. Caffeine and placebo were randomly assigned and ingested 1 h before exercise. In both experiments, ratings of perceived leg exertion were significantly lower during the fat + caffeine than fat-only trial (Experiment 1: P < 0.001; Experiment 2: P < 0.01). Ratings of perceived breathlessness were significantly lower in Experiment 1 (P < 0.01) and heart rate higher in Experiment 2 (P < 0.001) on the fat + caffeine than fat-only trial. In the two experiments, oxygen uptake, ventilation, blood [glucose], [lactate] and plasma [glycerol] were significantly higher on the fat + caffeine than fat-only trial. In Experiment 2, plasma [free fatty acids], blood [pyruvate] and the [lactate]:[pyruvate] ratio were significantly higher on the fat + caffeine than fat-only trial. Time to exhaustion during incremental exercise (Experiment 1: control: 4.9, s = 1.8 min; fat-only: 5.0, s = 2.2 min; fat + caffeine: 5.0, s = 2.2 min; P > 0.05) and constant-load exercise (Experiment 2: control: 116 (88 – 145) min; fat-only: 122 (96 – 144) min; fat + caffeine: 127 (107 – 176) min; P > 0.05) was not different between the fat-only and fat + caffeine trials. In conclusion, while a number of metabolic responses were increased during exercise after caffeine ingestion, perception of effort was reduced and this may be attributed to the direct stimulatory effect of caffeine on the central nervous system. However, this caffeine-induced reduction in effort perception did not improve exercise performance.

Carbohydrate ingestion during team games exercise

There is a growing body of research on the influence of ingesting carbohydrate-electrolyte solutions immediately prior to and during prolonged intermittent, high-intensity exercise (team games exercise) designed to replicate field-based team games. This review presents the current body of knowledge in this area, and identifies avenues of further research. Almost all early work supported the ingestion of carbohydrate-electrolyte solutions during prolonged intermittent exercise, but was subject to methodological limitations. A key concern was the use of exercise protocols characterized by prolonged periods at the same exercise intensity, the lack of maximal- or high-intensity work components and long periods of seated recovery, which failed to replicate the activity pattern or physiological demand of team games exercise. The advent of protocols specifically designed to replicate the demands of field-based team games enabled a more externally valid assessment of the influence of carbohydrate ingestion during this form of exercise. Once again, the research overwhelmingly supports carbohydrate ingestion immediately prior to and during team games exercise for improving time to exhaustion during intermittent running.While the external validity of exhaustive exercise at fixed prescribed intensities as an assessment of exercise capacity during team games may appear questionable, these assessments should perhaps not be viewed as exhaustive exercise tests per se, but as indicators of the ability to maintain high-intensity exercise, which is a recognized marker of performance and fatigue during field-based team games. Possible mechanisms of exercise capacity enhancement include sparing of muscle glycogen, glycogen resynthesis during low-intensity exercise periods and attenuated effort perception during exercise. Most research fails to show improvements in sprint performance during team games exercise with carbohydrate ingestion, perhaps due to the lack of influence of carbohydrate on sprint performance when endogenous muscle glycogen concentration remains above a critical threshold of ∼200 mmol/kg dry weight. Despite the increasing number of publications in this area, few studies have attempted to drive the research base forward by investigating potential modulators of carbohydrate efficacy during team games exercise, preventing the formulation of optimal carbohydrate intake guidelines. Potential modulators may be different from those during prolonged steady-state exercise due to the constantly changing exercise intensity and frequency, duration and intensity of rest intervals, potential for team games exercise to slow the rate of gastric emptying and the restricted access to carbohydrate-electrolyte solutions during many team games.This review highlights fluid volume, carbohydrate concentration, carbohydrate composition and solution osmolality; the glycaemic index of preexercise meals; fluid and carbohydrate ingestion patterns; fluid temperature; carbohydrate mouthwashes; carbohydrate supplementation in different ambient temperatures; and investigation of all of these areas in different subject populations as important avenues for future research to enable a more comprehensive understanding of carbohydrate ingestion during team games exercise.

Peak power, force, and velocity during jump squats in professional rugby players

Abstract Turner, AP, Unholz, CN, Potts, N, and Coleman, SGS. Peak power, force, and velocity during jump squats in professional rugby players. J Strength Cond Res 26(6): 1594–1600, 2012—Training at the optimal load for peak power output (PPO) has been proposed as a method for enhancing power output, although others argue that the force, velocity, and PPO are of interest across the full range of loads. The aim of this study was to examine the influence of load on PPO, peak barbell velocity (BV), and peak vertical ground reaction force (VGRF) during the jump squat (JS) in a group of professional rugby players. Eleven male professional rugby players (age, 26 ± 3 years; height, 1.83 ± 6.12 m; mass, 97.3 ± 11.6 kg) performed loaded JS at loads of 20–100% of 1 repetition maximum (1RM) JS. A force plate and linear position transducer, with a mechanical braking unit, were used to measure PPO, VGRF, and BV. Load had very large significant effects on PPO (p < 0.001, partial &eegr;2 = 0.915); peak VGRF (p < 0.001, partial &eegr;2 = 0.854); and peak BV (p < 0.001, partial &eegr;2= 0.973). The PPO and peak BV were the highest at 20% 1RM, though PPO was not significantly greater than that at 30% 1RM. The peak VGRF was significantly greater at 1RM than all other loads, with no significant difference between 20 and 60% 1RM. In resistance trained professional rugby players, the optimal load for eliciting PPO during the loaded JS in the range measured occurs at 20% 1RM JS, with decreases in PPO and BV, and increases in VGRF, as the load is increased, although greater PPO likely occurs without any additional load.

Unilateral vs. Bilateral Squat Training for Strength, Sprints, and Agility in Academy Rugby Players

Abstract Speirs, DE, Bennett, MA, Finn, CV, and Turner, AP. Unilateral vs. bilateral squat training for strength, sprints, and agility in academy rugby players. J Strength Cond Res 30(2): 386–392, 2016—The purpose of this study was to investigate the effects of a 5-week lower-limb unilateral or bilateral strength program on measures of strength, sprinting, and change of direction speed. Eighteen academy rugby players (18.1 ± 0.5 years, 97.4 ± 11.3 kg, 183.7 ± 11.3 cm) were randomly assigned to either a unilateral (UNI) or bilateral (BI) group. The UNI group squatted exclusively with the rear elevated split squat (RESS), whereas the BI group trained only with the bilateral back squat (BS). Both groups trained at a relative percentage of the respective 1 repetition maximum (1RM) twice weekly over a 5-week period. Subjects were assessed at baseline and postintervention for 1RM BS, 1RM RESS, 10-m sprint, 40-m sprint, and pro-agility. There was a significant main effect of time for 1RM BS (F1,16 = 86.5, p < 0.001), ES (0.84 < Cohen d < 0.92), 1RM RESS (F1,16 = 133.0, p < 0.001), ES (0.89 < Cohen d < 0.94), 40-m sprint (F1,16 = 14.4, p = 0.002), ES (0.47 < Cohen d < 0.67) and pro-agility (F1,16 = 55.9, p < 0.001), ES (0.77 < Cohen d < 0.89), but not 10-m sprints (F1,16 = 2.69, p = 0.121), ES (0.14 < Cohen d < 0.38). No significant interactions between group and time were observed for any of the dependent variables. This is the first study to suggest that BI and UNI training interventions may be equally efficacious in improving measures of lower-body strength, 40-m speed, and change of direction in academy level rugby players.

Using rhythmicity to promote performance in horizontal jumps: an exemplar of the need for individually-tailored interventions.

1 The current study compared and contrasted the optimal regulation of stride patterns in the 2 horizontal jumping events for 6 British athletes of international standard. Long jump and 3 triple jump approach data were collected over a 3-year period in international and domestic 4 competitions and considered against the distances achieved. Results suggest that on approach 5 to the take-off board, the majority of athletes’ jumps of greater length (intra-athlete) are 6 associated with a low variability, rhythmical footfall. Given the variable approach strategies 7 used by the athletes in question, and consequently the theoretical implications the data set 8 holds, tentative conclusions are drawn regarding the means by which scientists and coaches 9 should assess and design suitable performance focused interventions for elite performers 10 based on individual responses. 11 12 13 14 15 16 17 18 19 20 21 22 23 Horizontal Jump Performance Using Rhythmicity to Promote Performance in Horizontal Jumps: An Exemplar of the Need 1 for Individually-Tailored Interventions 2 Determining how skilled performers execute goal-directed behaviours and the means 3 that enable performance to be enhanced is an essential role which applied sport psychologists 4 often conduct in partnership with other scientists. In doing so, scientist-practitioners often 5 seek guidance from the prevailing theoretical and/or empirical paradigms before applying this 6 knowledge to the practical problem at hand. However, this may sometimes take thinking in 7 an erroneous or less than optimum direction, especially in the special cases of elite 8 performers. In this regard, recent evidence suggests that there are significant advantages to 9 examining how skilled performers organise movement patterns on an intra-individual basis, 10 despite commonalities in patterns of co-ordination being evident in participants of similar 11 ability. For example, Chow, Davids, Button, and Koh, (2006) stated that if skilled 12 participants are grouped together for the purposes of movement analysis, effects of interest, 13 such as control strategies may become masked. 14 Support for pursuing applied sport psychology on a case-by-case basis is illustrated by 15 an increasing number of studies that demonstrated individual-specific findings with reference 16 to performers’ coordination, their responses to appropriate sources of information for 17 instruction and adaptation to physical stress. For example, Beavan, Gill, and Cook (2008a) 18 demonstrated that professional rugby union players with broadly similar training backgrounds 19 responded to group-prescribed resistance training through individual hormonal responses. It 20 was determined that certain players responded positively to some training stresses, but not to 21 other forms of resistance training. In a 3-week cross-over design, the same players alternated 22 between sessions that produced high and low levels of testosterone. It was found that 23 favoured exercise selection elicited players’ maximum testosterone response and resulted in a 24 statistically significant strength gain. However, when the less favoured protocol was used, 25 Horizontal Jump Performance there was either no change, or a significant decline in tested strength (Beavan, Gill, & Cook, 1 2008b). Such individualised hormonal responses to training adaptations in professional sport 2 lend credence to the claim that advanced performers should be investigated on an individual 3 basis. 4 Further support for this contention is provided by examples of empirical research that 5 advocated the application of generic instructional principles to elite groups with—in some 6 cases—less than optimum results. Research carried out with shooters (e.g., rifle, pistol, and 7 archery) by Helin, Sihvonen, and Hanninen, (1987) and Landers, Christina, Hatfield, Daniels 8 and Doyle (1980) suggested that shooters performed to an optimised level when they shot in9 between heartbeats when the cardiac cycle is in diastole, or in what is termed the inter-beat 10 interval (IBI). However, analysis of case study data of six elite-level shooters conducted by 11 Bellamy, Collins, Holmes and Loze (1999) indicated that there is insufficient evidence to 12 advocate a universal strategy of shooting during diastole in elite shooters, since four of the 13 six shooters examined actually shot on the beat. Rather, they suggested the essential need for 14 checks that could detect individual patterns associated with better performance. Whilst this 15 example is somewhat dated, it is uncertain whether the application of generic instructions to 16 elite or advanced performers, albeit derived from peer-reviewed empirical work would 17 automatically result in an improvement to personal performance. 18 A more recent example of the contrasting instructional content of pre-performance 19 routines (PPRs) among elite golfers (i.e., mean handicap of +1.5) was uncovered by 20 Cotterrill, Sanders, and Collins (2010). Whilst the content and firing modality of PPRs has 21 been well researched in relation to self-paced skills (Singer, 2002), research conducted by 22 Cotterrill et al. (2010) showed that the development of a PPR for an elite golfer is 23 idiosyncratic; contingent upon their coping resources; factors that constitute their 24 personalities; and a tendency to appraise the context of each golf shot prior to task execution. 25 Horizontal Jump Performance Accordingly, we suggest that working uncritically from theory to intervention is not an 1 appropriate strategy for groups of advanced learners. 2 In light of these two examples (shooting & golf), it is important to reflect upon the 3 work of Newell, Liu, and Mayer-Kress (2005). Specifically, they proposed that different 4 types of information are differentially effective for athletes, and that the efficacy of 5 alternative sources of information is dependent on the task and the skill level of the learner. 6 Consequently, it is unlikely that an athlete’s potential will be maximised if a ‘one instruction 7 fits all’ approach is used. Therefore, the onus is on applied scientists to determine the most 8 effective sources of information to communicate with and inform athletes’ motor systems. 9 For example, in a study that provided concurrent auditory feedback to gymnasts on the 10 pommel horse, body segment alignment improved by 2.3% between the experimental and 11 control groups. Researchers concluded that auditory feedback provided in real-time could be 12 used to correct complex movements (Baudry, Leroy, Thouvarecq, & Chollet, 2006) as 13 opposed to the more commonly applied video techniques. Interestingly, anecdotal evidence 14 suggested that experienced horizontal jumps coaches could listen to the footfall of their 15 athletes, whilst looking in the opposite direction, and were able to confidently assert whether 16 their athlete had jumped well, or not (Moore, 2006). 17 Whilst it seems that some horizontal jumps coaches have become aware of, and 18 utilise, the rhythm engendered by the auditory output of an athlete’s footfall signature on 19 approach to the take-off board, there is interesting empirical research that has demonstrated 20 the beneficial effect of utilising an auditory output to augment visual information. In a 21 complex series of five experiments Vroomen and de Gelder (2000) demonstrated that 22 perceptual organisation in the auditory modality impacted upon perceptual accuracy in the 23 visual modality. Specifically, a high tone embedded in a series of low tones improved 24 detection of a visual target, when the visual target was presented at the same time – provided 25 Horizontal Jump Performance that the tone was abrupt and distinct from background noise or contaminating melodies. 1 These studies demonstrated that auditory stimuli can be used to enhance the detection of 2 visual information. Therefore, it is possible that a holistic rhythm of an athlete’s footfall prior 3 to contact with the take-off board may serve as an aid to improve foot-to-board accuracy – 4 provided an athlete’s footfall patterns are deemed to be relatively stable. 5 Whilst some athletes might not find this modality of movement correction useful, data 6 presented in this paper provide an opportunity for scientists, applied practitioners, and 7 coaches to consider the implications of working with elite performers through an exemplar of 8 this ‘individualised’ approach. Specifically, the applicability of prevailing theoretical 9 paradigms pertaining to the approach and preparation phases of horizontal jumps is critiqued 10 through consideration of data obtained from a cohort of elite performers. 11 Horizontal Jumps: Event demands 12 For athletes participating in horizontal jumps (HJ) the apparent difficulty associated 13 with executing the task lies in direct contrast to the simplicity of the objective. In particular, 14 the challenge rests in the trade-off between maintaining peak horizontal velocity (athletes 15 typically achieve peak horizontal velocities at take-off of 9.4 m/s for men, and 8.6 m/s for 16 women; see Linthorne, 2007) and being accurate on to the take-off board. To maximise the 17 measured distance, the space between the jump take-off and the edge of the take-off board 18 must be minimised. In addition, the athlete is required to create good ‘lift’ at take-off, 19 generating vertical impulse by accelerating body parts upwards during the final contact with 20 the board without employing large braking forces. A key factor in generating vertical lift is 21 the transference of horizontal velocity accrued on the run-up. Therefore, accuracy onto the 22 take-off board, at speed, is critical to eventual distance achieved (Hay, Miller, & Canterna, 23 1986). 24 Horizontal Jump Performance At an elite level the difficulty of “hitting the board” in HJ is exemplified by 1 1 participant in this investigation, an elite horizontal jumper, who had 10 years of