Test-retest reliability of a 30-min fixed perceived effort cycling exercise.

PURPOSE: Using exercise protocols at a fixed rating of perceived effort (RPE) is a useful method for exploring the psychophysical influences on exercise performance. However, studies that have employed this protocol have arbitrarily selected RPE values without considering how these values correspond to exercise intensity thresholds and domains. Therefore, aligning RPE intensities with established physiological thresholds seems more appropriate, although the reliability of this method has not been assessed. METHODS: Eight recreationally active cyclists completed two identical ramped incremental trials on a cycle ergometer to identify gas exchange threshold (GET). A linear regression model plotted RPE responses during this test alongside gas parameters to establish an RPE corresponding to GET (RPEGET) and 15% above GET (RPE+15%GET). Participants then completed three trials at each intensity, in which performance, physiological, and psychological measures were averaged into 5-min time zone (TZ) intervals and 30-min 'overall' averages. Data were assessed for reliability using intraclass correlation coefficients (ICC) and accompanying standard error measurements (SEM), 95% confidence intervals, and coefficient of variations (CoV). RESULTS: All performance and gas parameters showed excellent levels of test-retest reliability (ICCs = > .900) across both intensities. Performance, gas-related measures, and heart rate averaged over the entire 30-min exercise demonstrated good intra-individual reliability (CoV = < 5%). CONCLUSION: Recreationally active cyclists can reliably replicate fixed perceived effort exercise across multiple visits when RPE is aligned to physiological thresholds. Some evidence suggests that exercise at RPE+15%GET is more reliable than RPEGET.

Inter-day reliability of heart rate complexity and variability metrics in healthy highly active younger and older adults.

PURPOSE: To investigate the inter-day reliability of time-domain, frequency-domain, and nonlinear HRV metrics in healthy highly active younger and older adults. The study also assessed the effect of age on the HRV metrics. METHODS: Forty-four older adults (34 M, 10F; 59 ± 5 years; [Formula: see text] = 40.9 ± 7.6 ml kg-1 min-1) and twenty-two younger adults (16 M, 6F; 22 ± 4 years; [Formula: see text] = 47.2 ± 12.8 ml kg-1 min-1) attended the laboratory. Visit one assessed aerobic fitness through an exercise test. In visits two and three, participants completed a 30-min supine RR interval measurement to derive the HRV metrics. RESULTS: The younger group (YG) and older group (OG) demonstrated poor to good day-to-day relative and absolute reliability for all HRV metrics (OG, ICCs = 0.33 to 0.69 and between day CVs = 3.8 to 29.2%; YG, ICCs = 0.37 to 0.93 and between day CVs = 3.5 to 36.5%). There was a significant reduction in ApEn (P < 0.001), SampEn (P = 0.031), RMSSD (P < 0.001), SDNN (P < 0.001), LF power (P < 0.001) and HF power (P < 0.001), HRV metrics with ageing. There was no significant effect of age the complexity metrics DFA α1 (P = 0.107), α2 (P = 0.147) and CI-8 (P = 0.493). CONCLUSION: HRV metrics are reproducible between days in both healthy highly active younger and older adults. There is a decline in linear and nonlinear HRV metrics with age, albeit there being no age-related change in the nonlinear metrics, DFA α1, α2 and CI-8.

Functional threshold power and the (manufactured) critical power controversy.

We read with concern yet another communication from Dotan regarding the critical power (CP) concept which contains a litany of factual errors, false statements, and dated physiological interpretations. Space does not permit us to rebut every incorrect point made about our work (Wong et al., 2022) and the wider field in which it sits, but we will address what we consider to be some of the more egregious errors in his letter. We would first note, however, that our paper was not actually focused on the critical power concept.

The effect of hypertonic saline evoked muscle pain on neurophysiological changes and exercise performance in the contralateral limb.

Non-local muscle pain may impair endurance performance through neurophysiological mechanisms, but these are relatively unknown. This study examined the effects of muscle pain on neuromuscular and neurophysiological responses in the contralateral limb. On separate visits, nine participants completed an isometric time to task failure (TTF) using the right knee extensors after intramuscular injection of isotonic saline (CTRL) or hypertonic saline (HYP) into the left vastus lateralis. Measures of neuromuscular fatigue were taken before, during and after the TTF using transcranial magnetic stimulation (TMS) and peripheral nerve stimulation. Mean pain intensity was greater in the left leg in HYP (3.3 ± 1.9) compared to CTRL (0.4 ± 0.7; P < 0.001) which was combined with a reduced TTF by 9.8% in HYP (4.54 ± 0.56 min) compared to CTRL (5.07 ± 0.77 min; P = 0.005). Maximum voluntary force was not different between conditions (all P > 0.05). Voluntary activation was lower in HYP compared to CTRL (P = 0.022). No difference was identified between conditions for doublet amplitude (P > 0.05). Furthermore, no difference in MEP·Mmax-1 or the TMS silent period between conditions was observed (all P > 0.05). Non-local pain impairs endurance performance of the contralateral limb. This impairment in performance is likely due to the faster attainment of the sensory tolerance limit from a greater amount of sensory feedback originating from the non-exercising, but painful, left leg.

The effect of elevated muscle pain on neuromuscular fatigue during exercise.

PURPOSE: Muscle pain can impair exercise performance but the mechanisms for this are unknown. This study examined the effects of muscle pain on neuromuscular fatigue during an endurance task. METHODS: On separate visits, twelve participants completed an isometric time-to-task failure (TTF) exercise of the right knee extensors at ~ 20% of maximum force following an intramuscular injection of isotonic saline (CTRL) or hypertonic saline (HYP) into the vastus lateralis. Measures of neuromuscular fatigue were taken before, during and after the TTF using transcranial magnetic stimulation (TMS) and peripheral nerve stimulation. RESULTS: The mean pain intensity was 57 ± 10 in HYP compared to 38 ± 18 in CTRL (P < 0.001). TTF was reduced in HYP (4.36 ± 0.88 min) compared to CTRL (5.20 ± 0.39 min) (P = 0.003). Maximum voluntary force was 12% lower at minute 1 (P = 0.003) and 11% lower at minute 2 in HYP (P = 0.013) compared to CTRL. Voluntary activation was 4% lower at minute 1 in HYP compared to CTRL (P = 0.006) but not at any other time point (all P > 0.05). The TMS silent period was 9% longer at 100 s during the TTF in HYP compared to CTRL (P = 0.026). CONCLUSION: Muscle pain reduces exercise performance through the excacerbation of neuromuscular fatigue that is central in origin. This appears to be from inhibitory feedback from group III/IV nociceptors which acts to reduce central motor output.

Muscle pain induced by hypertonic saline in the knee extensors decreases single-limb isometric time to task failure.

PURPOSE: Increased nociceptive activity and the experience of exercise-induced pain (EIP) may contribute to fatigue during endurance exercise. To investigate this, a pain model that produces pain similar to EIP and decouples its relationship to exercise intensity is required. This study (1) compared the quality of pain caused by a hypertonic saline injection into the vastus lateralis in resting and exercise conditions, and (2) investigated whether this pain contributes to changes in time to task failure. METHODS: On separate days, 18 participants completed a time to task failure at 20% maximal voluntary torque (MVT), a resting hypertonic saline intramuscular injection, and in a further three visits a time to task failure at 10% MVT following injection of isotonic saline, hypertonic saline or a control (no injection). RESULTS: In a subset of eligible participants (n = 12), the hypertonic saline combined with 10% MVT produced a qualitative experience of pain (assessed by the McGill Pain Questionnaire) that felt similar to EIP. 10% MVT with hypertonic saline significantly elevated pain intensity in the first 20% of the time to task failure and caused a significantly (P < 0.05) shorter time to task failure (448 ± 240 s) compared with the isotonic saline (605 ± 285 s) and control (514 ± 197 s) conditions. CONCLUSION: These findings demonstrate that hypertonic saline increases the intensity of pain during exercise, which results in a faster occurrence of exercise-induced fatigue. These results provide important evidence supporting pain as a limiting factor in endurance performance.

Prescribing 6-weeks of running training using parameters from a self-paced maximal oxygen uptake protocol.

PURPOSE: The self-paced maximal oxygen uptake test (SPV) may offer effective training prescription metrics for athletes. This study aimed to examine whether SPV-derived data could be used for training prescription. METHODS: Twenty-four recreationally active male and female runners were randomly assigned between two training groups: (1) Standardised (STND) and (2) Self-Paced (S-P). Participants completed 4 running sessions a week using a global positioning system-enabled (GPS) watch: 2 × interval sessions; 1 × recovery run; and 1 × tempo run. STND had training prescribed via graded exercise test (GXT) data, whereas S-P had training prescribed via SPV data. In STND, intervals were prescribed as 6 × 60% of the time that velocity at [Formula: see text] ([Formula: see text]) could be maintained (Tmax). In S-P, intervals were prescribed as 7 × 120 s at the mean velocity of rating of perceived exertion 20 (vRPE20). Both groups used 1:2 work:recovery ratio. Maximal oxygen uptake ([Formula: see text]), [Formula: see text], Tmax, vRPE20, critical speed (CS), and lactate threshold (LT) were determined before and after the 6-week training. RESULTS: STND and S-P training significantly improved [Formula: see text] by 4 ± 8 and 6 ± 6%, CS by 7 ± 7 and 3 ± 3%; LT by 5 ± 4% and 7 ± 8%, respectively (all P < .05), with no differences observed between groups. CONCLUSIONS: Novel metrics obtained from the SPV can offer similar training prescription and improvement in [Formula: see text], CS and LT compared to training derived from a traditional GXT.

Transcutaneous electrical nerve stimulation reduces exercise-induced perceived pain and improves endurance exercise performance.

PURPOSE: Muscle pain is a natural consequence of intense and prolonged exercise and has been suggested to be a limiter of performance. Transcutaneous electrical nerve stimulation (TENS) and interferential current (IFC) have been shown to reduce both chronic and acute pain in a variety of conditions. This study sought to ascertain whether TENS and IFC could reduce exercise-induced pain (EIP) and whether this would affect exercise performance. It was hypothesised that TENS and IFC would reduce EIP and result in an improved exercise performance. METHODS: In two parts, 18 (Part I) and 22 (Part II) healthy male and female participants completed an isometric contraction of the dominant bicep until exhaustion (Part I) and a 16.1 km cycling time trial as quickly as they could (Part II) whilst receiving TENS, IFC, and a SHAM placebo in a repeated measures, randomised cross-over, and placebo-controlled design. Perceived EIP was recorded in both tasks using a validated subjective scale. RESULTS: In Part I, TENS significantly reduced perceived EIP (mean reduction of 12%) during the isometric contraction (P = 0.006) and significantly improved participants' time to exhaustion by a mean of 38% (P = 0.02). In Part II, TENS significantly improved (P = 0.003) participants' time trial completion time (~2% improvement) through an increased mean power output. CONCLUSION: These findings demonstrate that TENS can attenuate perceived EIP in a healthy population and that doing so significantly improves endurance performance in both submaximal isometric single limb exercise and whole-body dynamic exercise.

Age differences in physiological responses to self-paced and incremental [Formula: see text] testing.

PURPOSE: A self-paced maximal exercise protocol has demonstrated higher [Formula: see text] values when compared against traditional tests. The aim was to compare physiological responses to this self-paced [Formula: see text] protocol (SPV) in comparison to a traditional ramp [Formula: see text] (RAMP) protocol in young (18-30 years) and old (50-75 years) participants. METHODS: Forty-four participants (22 young; 22 old) completed both protocols in a randomised, counter-balanced, crossover design. The SPV included 5 × 2 min stages, participants were able to self-regulate their power output (PO) by using incremental 'clamps' in ratings of perceived exertion. The RAMP consisted of either 15 or 20 W min-1. RESULTS: Expired gases, cardiac output (Q), stroke volume (SV), muscular deoxyhaemoglobin (deoxyHb) and electromyography (EMG) at the vastus lateralis were recorded throughout. Results demonstrated significantly higher [Formula: see text] in the SPV (49.68 ± 10.26 ml kg-1 min-1) vs. the RAMP (47.70 ± 9.98 ml kg-1 min-1) in the young, but not in the old group (>0.05). Q and SV were significantly higher in the SPV vs. the RAMP in the young (<0.05) but not in the old group (>0.05). No differences seen in deoxyHb and EMG for either age groups (>0.05). Peak PO was significantly higher in the SPV vs. the RAMP in both age groups (<0.05). CONCLUSION: Findings demonstrate that the SPV produces higher [Formula: see text], peak Q and SV values in the young group. However, older participants achieved similar [Formula: see text] values in both protocols, mostly likely due to age-related differences in cardiovascular responses to incremental exercise, despite them achieving a higher physiological workload in the SPV.

Prediction of Overuse Injuries in Professional U18-U21 Footballers Using Metrics of Training Distance and Intensity.

Bacon, CS and Mauger, AR. Prediction of overuse injuries in professional U18-U21 footballers using metrics of training distance and intensity. J Strength Cond Res 31(11): 3067-3076, 2017-The most common injury in professional football is an overuse injury to the lower limb. A significant external risk factor of this injury is the mismanagement of training and match loads. The aim of the current study was to examine the predictability of overuse injuries in professional youth soccer players using volume and intensity variables derived from Global Positioning Systems. A total of 41 players (age: 17.8 ± 1.1 years) training and match loads were assessed. These external loads were measured over 2 competitive seasons for every training session and match for each individual. A linear regression was used to test the predictability of the injury based on load, which were grouped using loading groups calculated from squad weekly averages. The load groupings assigned were: low load = 1 SD below the squad mean score; normal load = ±1 SD from the squad mean; high load = 1 SD above squad mean. The analysis demonstrated that total distance significantly predicted overuse injury incidence rates (F 1,39 = 6.482, p = 0.015), whereas high-speed running meters could not (F 1,39 = 1.003, p = 0.323). This study demonstrated that distance covered in training and matches can impact on the incidence of overuse injury in youth soccer players. Coaches should seek to monitor player training loads and incorporate this metric into their decision making for protecting players from overuse injury.

The effect of transcranial direct current stimulation of the motor cortex on exercise-induced pain.

PURPOSE: Transcranial direct current stimulation (tDCS) provides a new exciting means to investigate the role of the brain during exercise. However, this technique is not widely used in exercise science, with little known regarding effective electrode montages. This study investigated whether tDCS of the motor cortex (M1) would elicit an analgesic response to exercise-induced pain (EIP). METHODS: Nine participants completed a VO2max test and three time to exhaustion (TTE) tasks on separate days following either 10 min 2 mA tDCS of the M1, a sham or a control. Additionally, seven participants completed 3 cold pressor tests (CPT) following the same experimental conditions (tDCS, SHAM, CON). Using a well-established tDCS protocol, tDCS was delivered by placing the anodal electrode above the left M1 with the cathodal electrode above dorsolateral right prefrontal cortex. Gas exchange, blood lactate, EIP and ratings of perceived exertion (RPE) were monitored during the TTE test. Perceived pain was recorded during the CPT. RESULTS: During the TTE, no significant differences in time to exhaustion, RPE or EIP were found between conditions. However, during the CPT, perceived pain was significantly (P < 0.05) reduced in the tDCS condition (7.4 ± 1.2) compared with both the CON (8.6 ± 1.0) and SHAM (8.4 ± 1.3) conditions. CONCLUSION: These findings demonstrate that stimulation of the M1 using tDCS does not induce analgesia during exercise, suggesting that the processing of pain produced via classic measures of experimental pain (i.e., a CPT) is different to that of EIP. These results provide important methodological advancement in developing the use of tDCS in exercise.

Effect of tyrosine ingestion on cognitive and physical performance utilising an intermittent soccer performance test (iSPT) in a warm environment.

PURPOSE: The aim of this study was to investigate the effect of tyrosine (TYR) ingestion on cognitive and physical performance during soccer-specific exercise in a warm environment. METHODS: Eight male soccer players completed an individualised 90 min soccer-simulation intermittent soccer performance test (iSPT), on a non-motorised treadmill, on two occasions, within an environmental chamber (25 °C, 40 % RH). Participants ingested tyrosine (TYR; 250 mL sugar free drink plus 150 mg kg body mass(-1) TYR) at both 5 h and 1 h pre-exercise or a placebo control (PLA; 250 mL sugar free drink only) in a double-blind, randomised, crossover design. Cognitive performance (vigilance and dual-task) and perceived readiness to invest physical effort (RTIPE) and mental effort (RTIME) were assessed: pre-exercise, half-time, end of half-time and immediately post-exercise. Physical performance was assessed using the total distance covered in both halves of iSPT. RESULTS: Positive vigilance responses (HIT) were significantly higher (12.6 ± 1.7 vs 11.5 ± 2.4, p = 0.015) with negative responses (MISS) significantly lower (2.4 ± 1.8 vs 3.5 ± 2.4, p = 0.013) in TYR compared to PLA. RTIME scores were significantly higher in the TYR trial when compared to PLA (6.7 ± 1.2 vs 5.9 ± 1.2, p = 0.039). TYR had no significant (p > 0.05) influence on any other cognitive or physical performance measure. CONCLUSION: The results show that TYR ingestion is associated with improved vigilance and RTIME when exposed to individualised soccer-specific exercise (iSPT) in a warm environment. This suggests that increasing the availability of TYR may improve cognitive function during exposure to exercise-heat stress.

Acute acetaminophen (paracetamol) ingestion improves time to exhaustion during exercise in the heat.

Acetaminophen (paracetamol) is a commonly used over-the-counter analgesic and antipyretic and has previously been shown to improve exercise performance through a reduction in perceived pain. This study sought to establish whether its antipyretic action may also improve exercise capacity in the heat by moderating the increase in core temperature. On separate days, 11 recreationally active participants completed two experimental time-to-exhaustion trials on a cycle ergometer in hot conditions (30°C, 50% relative humidity) after ingesting a placebo control or an oral dose of acetaminophen in a randomized, double-blind design. Following acetaminophen ingestion, participants cycled for a significantly longer period of time (acetaminophen, 23 ± 15 min versus placebo, 19 ± 13 min; P = 0.005; 95% confidence interval = 90-379 s), and this was accompanied by significantly lower core (-0.15°C), skin (-0.47°C) and body temperatures (0.19°C; P < 0.05). In the acetaminophen condition, participants also reported significantly lower ratings of thermal sensation (-0.39; P = 0.015), but no significant change in heart rate was observed (P > 0.05). This is the first study to demonstrate that an acute dose of acetaminophen can improve cycling capacity in hot conditions, and that this may be due to the observed reduction in core, skin and body temperature and the subjective perception of thermal comfort. These findings suggest that acetaminophen may reduce the thermoregulatory strain elicited from exercise, thus improving time to exhaustion.

The influence of acetaminophen on repeated sprint cycling performance.

INTRODUCTION: The aim of this study was to investigate the effect of acetaminophen on repeated sprint cycling performance. METHODS: Nine recreationally active male participants completed a graded exercise test, a familiarisation set of Wingate Anaerobic Tests (WAnTs) and two experimental sets of WAnTs (8 × 30 s sprints, 2 min active rest intervals). In the experimental WAnTs, participants ingested either 1.5 g acetaminophen or a placebo in a double-blind, randomised, crossover design. During the WAnT trials, participants provided ratings of perceived pain 20 s into each sprint. Mean and peak power output and heart rate were recorded immediately following each sprint, and percentage decrement in mean power output was subsequently calculated. RESULTS: Participants cycled at a significantly greater mean power output over the course of 8 WAnTs (p < 0.05) following the ingestion of acetaminophen (391 ± 74 vs. 372 ± 90 W), due to a significantly greater mean power output during sprints 6, 7 and 8 (p < 0.05). Percentage decrements in mean power output were also significantly reduced (p < 0.05) following acetaminophen ingestion (17 ± 14 vs. 24 ± 17 %). No significant differences in peak power output, perceived pain or heart rate were observed between conditions. CONCLUSION: Acetaminophen may have improved performance through the reduction of pain for a given work rate, thereby enabling participants to exercise closer to a true physiological limit. These results suggest that exercise may be regulated by pain perception, and that an increased pain tolerance can improve exercise performance.

The reliability and validity of a soccer-specific nonmotorised treadmill simulation (intermittent soccer performance test).

This study investigated the reliability and validity of a novel nonmotorised treadmill (NMT)-based soccer simulation using a novel activity category called a "variable run" to quantify fatigue during high-speed running. Twelve male University soccer players completed 3 familiarization sessions and 1 peak speed assessment before completing the intermittent soccer performance test (iSPT) twice. The 2 iSPTs were separated by 6-10 days. The total distance, sprint distance, and high-speed running distance (HSD) were 8,968 ± 430 m, 980 ± 75 m and 2,122 ± 140 m, respectively. No significant difference (p > 0.05) was found between repeated trials of the iSPT for all physiological and performance variables. Reliability measures between iSPT1 and iSPT2 showed good agreement (coefficient of variation: <4.6%; intraclass correlation coefficient: >0.80). Furthermore, the variable run phase showed HSD significantly decreased (p ≤ 0.05) in the last 15 minutes (89 ± 6 m) compared with the first 15 minutes (85 ± 7 m), quantifying decrements in high-speed exercise compared with the previous literature. This study validates the iSPT as a NMT-based soccer simulation compared with the previous match-play data and is a reliable tool for assessing and monitoring physiological and performance variables in soccer players. The iSPT could be used in a number of ways including player rehabilitation, understanding the efficacy of nutritional interventions, and also the quantification of environmentally mediated decrements on soccer-specific performance.

Precooling does not improve 2,000-m rowing performance of females in hot, humid conditions.

Precooling lowers skin (Tsk) and core temperature (Tre) and can improve performance in hot conditions, but has predominantly been studied in males. This study investigated the effects of precooling on self-paced 2,000-m rowing performance, within females, in hot, humid conditions. Eight physically active females (19.9 ± 1.5 years, 66.8 ± 3.1 kg, 30.0 ± 5.0% body fat) performed 2,000-m rows in a randomized order within 3 conditions {control (CONT) (20° C, 40% relative humidity [RH]); hot (HOT) (35° C, 60% RH); precooling (PREC) (35° C, 60% RH, preceded by precooling)}. The precooling condition consisted of 20-minute precooling with a cold water shower, followed by a 2,000-m row. In contrast, CONT and HOT consisted of 20-minute passive rest in place of precooling. Tre, Tsk, and power output were recorded every 100 m of the rows. Muscle temperature (Tmu) was recorded at baseline, after 20-minute passive rest/precooling and post-row. No differences were observed between conditions for performance time (CONT, 8.89 ± 0.45 minutes; HOT, 9.01 ± 0.55 minutes; PREC, 8.87 ± 0.48 minutes; p = 0.42). Mean Tre during the row was not different between conditions (CONT, 37.8 ± 0.2° C; HOT, 37.7 ± 0.3° C; PREC, 37.5 ± 0.2° C; p = 0.12; main effect), although lower Tre was observed at 1,600 and 1,800 m in PREC compared with HOT (p ≤ 0.05). Tmu was significantly reduced after precooling (p = 0.03). Precooling did not enhance 2,000-m rowing performance, despite differences in Tre, Tsk, and Tmu. The lack of observed improvement in rowing performance after cold shower precooling may have been due to the short exercise time. An improvement in performance may have been observed using an alternate method of precooling, which has been shown to be ergogenic in other sports.

RPE-derived work rates can be accurately produced without external feedback or reference to the RPE Scale.

Ratings of perceived exertion (RPE) are used to prescribe exercise intensity. This study assessed whether the accurate production of exercise intensity is affected when the rater cannot see the RPE scale. After completing a graded exercise test, 15 active, male participants (M age = 34, SD = 6.7 yr.; M mass = 73.9, SD = 14.8kg, M height = 1.74, SD = 0.08m) completed 3 x 4 min. cycling trials at four randomised RPE-based intensities (RPEs 11, 13, 15, and 17). Participants were allocated to a Full feedback group or a No feedback group (RPEs not in view). On the third trial, No feedback conditions were imposed on the Full feedback group. No statistically significant differences between groups' mean work rates were observed. Changing from Full feedback to No feedback conditions led to a significant overestimation between the trials for power output at RPE 11. Intra-class correlations were significant at RPEs 11, 13, and 17 between all trials for both conditions. Provided adequate familiarisation, active participants can accurately produce RPE derived work rates, even when RPE is not in view.

The effect of different environmental conditions on the decision-making performance of soccer goal line officials.

Goal line officials (GLO) are exposed to extreme environmental conditions when employed to officiate in professional European soccer cup competitions. The present study aimed to investigate the effect of such environments on GLO decision-making ability. Thirteen male participants were exposed to three conditions: cold (-5°C, 50% relative humidity (RH)); temperate (18°C, 50% RH); and hot (30°C, 50% RH) for 90 min per condition, with a 15 min half-time break after 45 min. Decision-making ability was assessed throughout the 90 min exposure. Core and skin temperatures were recorded throughout. Decision making was improved during exposure to the temperate condition when compared with the cold (mean difference = 12.5%; 95% CI = 1.1%, 23.9%; P = 0.031). Regression analysis indicated that as skin temperature increases so does decision-making ability. Exposure to cold conditions diminished the decision-making ability of GLO.

The effect of acetaminophen ingestion on cortico-spinal excitability.

Acetaminophen (ACT) facilitates the inhibition of voltage-gated calcium and sodium currents, which may effect cortico-spinal excitability. Twelve subjects ingested acetaminophen or a placebo and underwent transcranial magnetic stimulation to assess the motor evoked potential (MEP), and cortical silent period (CSP). ACT significantly increased MEP response (P > 0.05) but had no effect on CSP (P > 0.05). This indicates that ACT increases MEP and should be controlled for in studies where these measures are of interest.

Partial heat acclimation of athletes with spinal cord lesion.

Heat acclimation (HA) can improve thermoregulatory stability in able-bodied athletes in part by an enhanced sweat response. Athletes with spinal cord lesion are unable to sweat below the lesion and it is unknown if they can HA. Five paralympic shooting athletes with spinal cord lesion completed seven consecutive days HA in hot conditions (33.4 ± 0.6 °C, 64.8 ± 3.7 %rh). Each HA session consisted of 20 min arm crank exercise at 50 % [Formula: see text] followed by 40 min rest, or simulated shooting. Aural temperature (T (aur)) was recorded throughout. Body mass was assessed before and after each session and a sweat collection swab was fixed to T12 of the spine. Fingertip whole blood was sampled at rest on days 1 and 7 for estimation of the change in plasma volume. Resting T (aur) declined from 36.3 ± 0.2 °C on day 1 to 36.0 ± 0.2 °C by day 6 (P < 0.05). During the HA sessions mean, T (aur) declined from 37.2 ± 0.2 °C on day 1, to 36.7 ± 0.3 °C on day 7 (P < 0.05). Plasma volume increased from day 1 by 1.5 ± 0.6 % on day 7 (P < 0.05). No sweat secretion was detected or changes in body mass observed from any participant. Repeated hyperthermia combined with limited evaporative heat loss was sufficient to increase plasma volume, probably by alterations in fluid regulatory hormones. In conclusion, we found that although no sweat response was observed, athletes with spinal cord lesion could partially HA.