Physiological Response Differences between Run and Cycle High Intensity Interval Training Program in Recreational Middle Age Female Runners.

The aim of this investigation was to compare the changes in endurance running performance and physiological variables after a four-week period of high intensity interval training (HIIT) in either running or cycling in female athletes. Fourteen recreational female runners (age = 42 10 yr, height = 1.67 0.06 m, body mass = 61.6 10.4 kg, body mass index (BMI) = 22.2 3.4 kg.m-2) were randomly allocated to one of two HIIT training groups: running (HIITrun) or cycling (HIITbike). Each group performed two HIIT sessions per week for 4 weeks, which consisted of 6 x 2 min at 95% of maximal heart rate (HRmax) and 4 x 1 min all out efforts. Maximal oxygen consumption (VO2max) in treadmill running increased significantly after the HIITrun (p < 0.01, ES = 0.6) but remained unchanged in HIITbike. However, HIITbike improved average velocity in a 10 km running time trial (TTrun) (p < 0.05, ES = -0.4), whereas, no changes were found for the HIITrun group. Analysing the first and last HIIT sessions, for HIITrun only the average rate of perceived exertion (RPEav) increased significantly, whereas, performance variables such as average heart rate (HRav) and average pace (paceav) remained unchanged. HIITbike enhanced significantly the average speed of HIIT sets (speedav) and the peak power output (PPO) of the session, as well as, the RPEav and delayed onset muscle soreness immediately after HIIT session (DOMSpost) were increased significantly. A regime of HIIT in cycling may evoke increases in female recreational runners' power, which may be related with improvements in a 10 km TTrun independent of changes in aerobic capacity. This may be advantageous in order to avoid overuse running related injuries.

Sodium bicarbonate ingestion and individual variability in time-to-peak pH.

This study determined variability in time-to-peak pH after consumption of 300 mg kg-1 of sodium bicarbonate. Seventeen participants (mean ± SD: age 21.38 ± 1.5 years; mass 75.8 ± 5.8 kg; height 176.8 ± 7.6 cm) reported to the laboratory where a resting capillary sample was taken. Then, 300 mg kg-1 of NaHCO3 in 450 ml of flavoured water was ingested. Participants rested for 90 min and repeated blood samples were procured at 10 min intervals for 60 min and then every 5 min until 90 min. Blood pH concentrations were measured. Results suggested that time-to-peak pH (64.41 ± 18.78 min) was variable with a range of 10-85 min and a coefficient of variation of 29.16%. A bimodal distribution occurred, at 65 and 75 min. In conclusion, athletes, when using NaHCO3 as an ergogenic aid, should determine their time-to-peak pH to best utilize the added buffering capacity this substance allows.

Ingestion of a Nitric Oxide Enhancing Supplement Improves Resistance Exercise Performance.

Mosher, SL, Sparks, SA, Williams, EL, Bentley, DJ, and Mc Naughton, LR. Ingestion of a nitric oxide enhancing supplement improves resistance exercise performance. J Strength Cond Res 30 (12): 3520-3524, 2016-Studies have established that supplementation of nitrate increases nitric oxide which in turn improves exercise performance. The current study aimed to investigate the effects of nitrate ingestion on performance of bench press resistance exercise until failure. Twelve recreationally active (age, 21 ± 2 years, height, 177.2 ± 4.0 cm, weight, 82.49 ± 9.78 kg) resistance-trained men participated in the study. The study used a double-blind, randomized cross-over design, where participants ingested either 70 ml of "BEET It Sport" nitrate shot containing 6.4 millimoles (mmol·L) or 400 mg of nitrate or a blackcurrant placebo drink. Participants completed a resistance exercise session, consisting of bench press exercise at an intensity of 60% of their established 1 repetition maximum (1RM), for 3 sets until failure with 2 minutes rest interval between sets. The repetitions completed, total weight lifted, local and general rate of perceived exertion (RPE), and blood lactate were all measured. The results showed a significant difference in repetitions to failure (p ≤ 0.001) and total weight lifted (p ≤ 0.001). However, there were no significant difference between blood lactate over the 2 trials (p = 0.238), and no difference in Local (p = 0.807) or general (p = 0.420) indicators of fatigue as measured by RPE. This study demonstrates that nitrate supplementation has the potential to improve resistance training performance and work output compared with a placebo.

The Effects of Novel Ingestion of Sodium Bicarbonate on Repeated Sprint Ability.

This work examined the influence of an acute dose of sodium bicarbonate (NaHCO3) on buffering capacity and performance during a repeated sprint ability (RSA) protocol. Eleven (mean ± SD: age 24.6 ± 6.1 years; mass 74.9 ± 5.7 kg; height 177.2 ± 6.7 cm) participated in the study, undertaking 4 test sessions. On the first visit to the laboratory, each participant ingested 300 mg · kg(-1) of NaHCO3 (in 450 ml of flavored water) and blood samples were obtained at regular intervals to determine the individual times peak pH and HCO3. In subsequent visits, participants ingested 300 mg · kg(-1) of NaHCO3, 270 mg · kg(-1) body mass (BM) of NaCI, or no drink followed by a RSA cycling protocol (10 × 6 seconds sprints with 60 seconds recovery), which commenced at each individuals predetermined ingestion peak pH response time. Blood samples were obtained before exercise and after the first, fifth, and 10th sprint to determine the blood pH, HCO3, and lactate (La) responses. Total work completed during the repeated sprint protocol was higher (p ≤ 0.05) in the NaHCO3 condition (69.8 ± 11.7 kJ) compared with both the control (59.6 ± 12.2 kJ) and placebo (63.0 ± 8.3 kJ) conditions. Peak power output was similar (p > 0.05) between the 3 conditions. Relative to the control and placebo conditions, NaHCO3 ingestion induced higher (p ≤ 0.05) blood pH and HCO3 concentrations before exercise and during the bouts, and higher lactate concentrations (p ≤ 0.05) after the final sprint. Results suggest that NaHCO3 improves the total amount of work completed during RSA through enhanced buffering capacity.

Interval training versus continuous exercise in patients with coronary artery disease: a meta-analysis.

BACKGROUND: High aerobic capacity is inversely related to cardiovascular disease morbidity and mortality. Recent studies suggest greater improvements in aerobic capacity with high-intensity interval training (interval) compared to moderate-intensity continuous aerobic exercise (continuous). Therefore we perform a meta-analysis of randomised controlled trials comparing the effectiveness of INTERVAL versus CONTINUOUS in aerobic capacity, amongst patients with stable coronary artery disease (CAD) and preserved ejection fraction METHODS: We searched PubMed, EMBASE, CINAHL, the Australia and New Zealand Clinical Trials Register, clinicaltrials.gov and TROVE for randomised controlled trials comparing INTERVAL with CONTINUOUS in patients with CAD. Studies published in the English language up to December 2013 were eligible for inclusion. Aerobic capacity, quantified by peak oxygen consumption (VO2peak) post exercise training was extracted and compared post-intervention between INTERVAL and CONTINUOUS by way of a fixed model meta-analysis. Secondary outcomes including anaerobic threshold, blood pressure and high-density lipoproteins (HDL) were also analysed. RESULTS: Six independent studies with 229 patients (n=99 randomised to INTERVAL) were included in the meta-analysis. There was a significantly higher increase in VO2peak following INTERVAL compared to CONTINUOUS (Weighted Mean Difference=1.53 ml•kg(-1)min(-1), 95% CI 0.84 to 2.23) with homogeneity displayed between studies (Chi Squared=2.69; P=0.7). Significant effects of INTERVAL compared to CONTINUOUS were also found for anaerobic threshold but not systolic blood pressure. CONCLUSION: In patients with CAD, INTERVAL appears more effective than CONTINUOUS for the improvement of aerobic capacity in patients with CAD. However, long-term studies assessing morbidity and mortality following INTERVAL are required before this approach can be more widely adopted.

Acute antioxidant supplementation improves endurance performance in trained athletes.

This study examined the acute effects of a single dose of an antioxidant (AO; Lactaway® containing pycnogenol) on time to fatigue (TTF). Nine trained cyclists [mean ± SD age 35 ± 10 yrs; body mass 71.6 ± 10.2 kg; VO2 peak 63 ± 11 ml/kg/min] performed on two separate occasions a continuous protocol of 5 min at 50% of peak power output (PPO), 8 min at 70% of PPO, and then cycled to fatigue at 95% PPO. Four hours prior to the exercise protocol, the subjects consumed the supplement or a placebo (counterbalanced, double blind protocol). Cyclists, on average, rode for 80 s more in the Lactaway trial than they did in the placebo trial. There was considerable evidence (chances ≥94.5%) for substantial positive treatment effects for TTF and the other performance-related variables (excluding [BLa] at 95% PPO). Other studies are necessary to confirm these results and identify the mechanisms underlying the observed effects.

Reliability and validity of physiological data obtained within a cycle-run transition test in age-group triathletes.

This study examined the validity and reliability of a sequential "Run-Bike-Run" test (RBR) in age-group triathletes. Eight Olympic distance (OD) specialists (age 30.0 ± 2.0 years, mass 75.6 ± 1.6 kg, run VO2max 63.8 ± 1.9 ml· kg(-1)· min(-1), cycle VO2peak 56.7 ± 5.1 ml· kg(-1)· min(-1)) performed four trials over 10 days. Trial 1 (TRVO2max) was an incremental treadmill running test. Trials 2 and 3 (RBR1 and RBR2) involved: 1) a 7-min run at 15 km· h(-1) (R1) plus a 1-min transition to 2) cycling to fatigue (2 W· kg(-1) body mass then 30 W each 3 min); 3) 10-min cycling at 3 W· kg(-1) (Bsubmax); another 1-min transition and 4) a second 7-min run at 15 km· h(-1) (R2). Trial 4 (TT) was a 30-min cycle - 20-min run time trial. No significant differences in absolute oxygen uptake (VO2), heart rate (HR), or blood lactate concentration ([BLA]) were evidenced between RBR1 and RBR2. For all measured physiological variables, the limits of agreement were similar, and the mean differences were physiologically unimportant, between trials. Low levels of test-retest error (i.e. ICC <0.8, CV<10%) were observed for most (logged) measurements. However [BLA] post R1 (ICC 0.87, CV 25.1%), [BLA] post Bsubmax (ICC 0.99, CV 16.31) and [BLA] post R2 (ICC 0.51, CV 22.9%) were least reliable. These error ranges may help coaches detect real changes in training status over time. Moreover, RBR test variables can be used to predict discipline specific and overall TT performance. Cycle VO2peak, cycle peak power output, and the change between R1 and R2 (deltaR1R2) in [BLA] were most highly related to overall TT distance (r = 0.89, p < 0. 01; r = 0.94, p < 0.02; r = 0.86, p < 0.05, respectively). The percentage of TR VO2max at 15 km· h(-1), and deltaR1R2 HR, were also related to run TT distance (r = -0.83 and 0.86, both p < 0.05).

Metabolic and Performance Responses to a Simulated Routine in Elite Artistic Swimmers.

The purpose of this investigation was to examine the interrelationship between time spent underwater (UW), movement frequency and accompanying blood acid base balance response. Elite artistic swimmers (n = 6) participated in the investigation and were all familiar with the testing procedures. All athletes completed the same choreographed artistic swimming routine. The routine was videoed and the number of movements during each 'lap' of the routine counted. Fingertip capillary blood samples were collected prior to the routine 60 sec post routine for pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), bicarbonate (HCO3-) and potassium (K+). and lactate (La) concentration (mmol/L). On a separate day an incremental exercise test to exhaustion was performed on a cycle ergometer for determination of maximal oxygen uptake (VO2max). Over half the routine was performed underwater (56 ± 4%). Aside from pCO2 (-1.07 ± 12.29%, p = 0.686), there were significant changes in all variables measured from the BG analysis. VO2peak was significantly correlated to total UW of the routine (r = -0.93; p = 0.007). as well as ∆PO2 r = 0.47 and ∆HCO3 r = 0.51. There was also a significant correlation between total UW and post routine pCO2 (r = 0.86; p = 0.030). There was also a significant correlation between total movements during the routine and post pO2 (r = -0.83; p = 0.044). These data show UW in combination with movement rate during a AS routine imfluence the metabolic response to the exercise. In addition, VO2max represents an important performance variable influencing AS performance.

Acute Physiological Response to Different Sprint Training Protocols in Normobaric Hypoxia.

BACKGROUND: the purpose of this study was to examine acute physiological responses to and the performance effects of two sprint training protocols in normobaric hypoxic conditions. METHODS: Healthy competitive female (n = 2) and male (n = 5) kayakers (19 ± 2.1 years) performed four sprint training sessions on a kayak ergometer over a period of two weeks. Participants performed five sets of 12 × 5 s sprints or 3 × 20 s sprints in both normobaric normoxic (NOR, FiO2 = 20.9%) or normobaric hypoxic (HYP, FiO2 = 13.6%) conditions. The peak power output (PPO), rate of perceived exertion (RPE), and heart rate (HR) of each participant were monitored continuously. Their blood lactate concentrations ([BLa+]), in addition to their blood gas (mixed-venous partial pressure (p) of carbon dioxide (pCO2), O2 (pO2), and oxygen saturations (sO2)) were collected before and after exercise. RESULTS: A significantly greater RPE, HR, and [BLa+] response and a significant decrease in pCO2, pO2, and sO2 were observed in HYP conditions versus NOR ones, independent of the type of training session. The PPO of participants did not differ between sessions. Their RPE in HYP12 × 5 was greater compared to all other sessions. CONCLUSIONS: The HYP conditions elicited significantly greater physiological strain compared to NOR conditions and this was similar in both training sessions. Our results suggest that either sprint training protocol in HYP conditions may induce more positive training adaptations compared to sprint training in NOR conditions.

The Effects of Anaerobic Swim Ergometer Training on Sprint Performance in Adolescent Swimmers.

PURPOSE: The purpose of this study was to compare 4 weeks of pool-based sprint interval training with a similar ergometer training intervention on a maximal anaerobic lactate test (MANLT), 50-m (competition) freestyle performance, and 6- and 30-second maximal swimming ergometer performances. METHODS: A total of 14 competitive adolescent swimmers (male, n = 8; female, n = 6) participated in this study. Swimmers were categorized into 2 sex-matched groups: swimming ergometer (ERG; n = 7) and pool-sprint training (n = 7) groups. Each athlete performed 4 preintervention and postintervention assessments consisting of a MANLT, a 50-m freestyle race, and 6- and 30-second maximal swim ERG performances. RESULTS: Both groups demonstrated a significant effect (P < .05) of time for all assessments. Group differences were observed after 4 weeks of sprint interval training as follows: (1) The ERG group had a significantly faster speed in the fourth 50-m MANLT sprint (ERG 1.58 [0.05] vs pool-sprint training 1.48 [0.07] m/s, P < .01) and (2) The ERG group demonstrated enhanced Δblood lactate post-MANLT (ERG 2.4 [1.2] vs pool-sprint training 2.7 [0.9] mmol/L, P < .05). A significant correlation was found between the 30-second maximal ERG test and 50-m freestyle swimming velocity (r = .74, P < .01, effect size = 0.52). CONCLUSIONS: The results demonstrate significant physiological improvements to anaerobic sprint ability after 4 weeks of sprint interval training in both swim ERG and pool-based interventions. Thus, sprint ability may be improved through multiple modalities (pool and dry land) to elicit a positive training response.

Applicability of Maximal Ergometer Testing and Sprint Performance in Adolescent Endurance and Sprint Trained Swimmers.

Sprint swimming is a short duration, high intensity sport requiring a relatively greater contribution of energy from anaerobic metabolism. Understanding energy system utilization for the classification of a competitive swimmer (sprint or distance) may be useful for both training prescription and event specialization. The relationship between anaerobic swim ergometer testing and adolescent sprint swimming performance has not been investigated. The purpose of this study was to compare the performance and physiological responses during a maximal all-out ergometer test as well as the maximal anaerobic lactate test in a group of sprint vs. middle-distance specialized swimmers. Sixteen (n = 16) competitive swimmers (mean ± standard deviation (SD), age 16.8 ± 0.7 year; body mass 67.3 ± 9.8 kg) were categorized into two gender matched groups: sprint (n = 8) and middle-distance (n = 8). Each athlete performed (1) a 45 s swim ergometer maximal test to determine peak and mean power output (Watts (W)), (2) a MANLT test to determine peak and average velocity as well as the post-exercise lactate response, and (3) a 50 m swim time trial. The sprint group showed a higher mean (p = 0.026) and peak (p = 0.031) velocity during the MANLT. In addition, blood lactate concentration was significantly (p < 0.01) higher in the sprint vs. middle-distance trained group at 3 and 12 min after completion of the MANLT (3-min post 11.29 ± 2.32 vs. 9.55 ± 3.48 mmol/L; 12-min post 8.23 ± 2.28 vs. 7.05 ± 2.47 mmol/L). The power output during the 45 s all-out swimming ergometer test was higher in the sprint trained group. The results of this study demonstrate the anaerobic contribution to sprint swimming measured during an all-out dryland ergometer test.

Menthol Mouth Rinsing Is More Than Just a Mouth Wash-Swilling of Menthol to Improve Physiological Performance.

Interventions that solely act on the central nervous system (CNS) are gaining considerable interest, particularly products consumed through the oral cavity. The oropharyngeal cavity contains a wide array of receptors that respond to sweet, bitter, and cold tastants, all of which have been shown to improve physiological performance. Of late, the ergogenic benefits of carbohydrate (CHO) and caffeine (CAF) mouth rinsings (MRs) have been widely studied; however, less is known about menthol (MEN). That the physiological state and environmental conditions impact the response each product has is increasingly recognized. While the effects of CHO and CAF MRs have been thoroughly studied in both hot and thermoneutral conditions, less is known about MEN as it has only been studied in hot environments. As such, this review summarizes the current knowledge regarding the MEN MR and exercise modality, frequency of the mouth rinse, and mouth rinse duration and compares two different types of study designs: time trials vs. time to exhaustion (TTE).

Adrenergic-beta(2) receptor polymorphism and athletic performance.

The focus of this review is to evaluate the influence of beta(2)-adrenergic receptor (ADRB2) polymorphism on human physiological function and in turn on athletic performance. A narrative review is conducted on available literature using MedLine, Pubmed and the Cochrane Library to document the location and function of ADRB2 receptors, and specifically to address the influence of genetic polymorphisms on cardiovascular, respiratory, metabolic and musculoskeletal systems and athletic performance. Search terms included ADRB2, endurance and polymorphism. Previous literature exploring the genetic composition of athletes has proposed that alterations in the genetic structure result in an enhancement in their capacity to achieve successful aerobic phenotypes such as a higher VO(2max) and increased fat oxidation. Polymorphism of the Gly16Glu27 haplotype is believed to promote positive aerobic phenotypes and regulate optimal lipolysis. Greater knowledge of the ADRB2 polymorphism can aid in understanding the specific phenotypes that are altered, which may influence performance. Until the interaction between fatigue and athletic performance is better understood, the development of appropriate training principles to enhance genetically polymorphic aerobic phenotypes remains complicated. Following the review, there is still no distinctive evidence for the predictive ability of the polymorphism of ADRB2 genotype for the purpose of identifying potential elite athletes.

Triathlon event distance specialization: training and injury effects.

We conducted a preliminary, questionnaire-based, retrospective analysis of training and injury in British National Squad Olympic distance (OD) and Ironman distance (IR) triathletes. The main outcome measures were training duration and training frequency and injury frequency and severity. The number of overuse injuries sustained over a 5-year period did not differ between OD and IR. However, the proportions of OD and IR athletes who were affected by injury to particular anatomical sites differed (p < 0.05). Also, fewer OD athletes (16.7 vs. 36.8%, p < 0.05) reported that their injury recurred. Although OD sustained fewer running injuries than IR (1.6 +/- 0.5 vs. 1.9 +/- 0.3, p < 0.05), more subsequently stopped running (41.7 vs. 15.8%) and for longer (33.5 +/- 43.0 vs. 16.7 +/- 16.6 days, p < 0.01). In OD, the number of overuse injuries sustained inversely correlated with percentage training time, and number of sessions, doing bike hill repetitions (r = -0.44 and -0.39, respectively, both p < 0.05). The IR overuse injury number correlated with the amount of intensive sessions done (r = 0.67, p < 0.01 and r = 0.56, p < 0.05 for duration of "speed run" and "speed bike" sessions). Coaches should note that training differences between triathletes who specialize in OD or IR competition may lead to their exhibiting differential risk for injury to specific anatomical sites. It is also important to note that cycle and run training may have a "cumulative stress" influence on injury risk. Therefore, the tendency of some triathletes to modify rather than stop training when injured-usually by increasing load in another discipline from that in which the injury first occurred-may increase both their risk of injury recurrence and time to full rehabilitation.

A Contemporary Variable-Power Cycling Protocol to Discriminate Race-Specific Performance Ability.

PURPOSE: Traditional physiological testing and monitoring tools have restricted our ability to capture parameters that best relate to cycling performance under variable-intensity race demands. This study examined the validity of a 1-h variable cycling test (VCT) to discriminate between different-performance-level cyclists. METHODS: Ten male national- and 13 club-level cyclists (body mass, 67 [9] and 79 [6] kg; peak power output, 359 [43] and 362 [21] W, respectively) completed a VO2max test and two 1-h VCT protocols on 3 separate occasions. The VCT consisted of 10 × 6-min segments containing prescribed (3.5 W·kg-1) and open-ended phases. The open-ended phases consisted of 4 × 30-40 s of "recovery," 3 × 10 s at "hard" intensity, and 3 × 6-s "sprint" with a final 10-s "all-out" effort. RESULTS: Power output for the 6- and 10-s phases was moderately higher for the national- compared with club-level cyclists (mean [SD] 10.4 [2.0] vs 8.6 [1.6] W·kg-1, effect size; ±90% confidence limits = -0.87; ±0.65 and mean [SD] 7.5 [0.7] vs 6.2 [1.0] W·kg-1, effect size; ±90% confidence limits = -1.24; ±0.66, respectively). Power output for the final 10-s "all-out" sprint was 15.4 (1.5) for the national- versus 13.2 (1.9) W·kg-1 for club-level cyclists. CONCLUSION: The 1-h VCT can successfully differentiate repeat high-intensity effort performance between higher-caliber cyclists and their lower-performing counterparts.

Relationship between VO 2max , under Water Swim Testing and Artistic Swim Solo Performance.

The purpose of this study was to evaluate the relationship between: 1) laboratory-determined cycling peak oxygen consumption (VO 2max ) and AS performance in a new underwater swim test (UWST), and 2) cycling VO 2max and ventilatory threshold (VT) in cycling and performance score during a simulated AS solo routine. Trained artistic swimmers (n=15, 15.8±0.8 yrs., height: 169.1±5.4 cm, body mass: 57.1±6.3 kg) completed (1) a maximal incremental cycle test to exhaustion to determine VO 2max , (2) the UWST which comprised 275 m of freestyle and underwater breaststroke, and (3) a simulated solo competition where artistic swimming elements were evaluated by five FINA judges. There was a significant correlation between mean element score and (i) VO 2max (48±4 mL . kg . min -1 , r=0.44, p =0.05), and (ii) UWST (r=-0.64, p =0.005). However, there was an insignificant relationship between cycling ventilatory threshold and mean element score (r=-0.36, p =0.10). In addition, the results demonstrate a significant relationship between HR at the ventilatory threshold and peak HR of the UWST (r=-0.64, p =0.014). The results of this study demonstrate that VO 2max is an important determinant of AS performance. In addition, the UWST appears to be a useful indicator of AS performance.

Locomotor exercise induces long-lasting impairments in the capacity of the human motor cortex to voluntarily activate knee extensor muscles.

Muscle fatigue is a reduction in the capacity to exert force and may involve a "central" component originating in the brain and/or spinal cord. Here we examined whether supraspinal factors contribute to impaired central drive after locomotor endurance exercise. On 2 separate days, 10 moderately active individuals completed a locomotor cycling exercise session or a control session. Brief (2 s) and sustained (30 s) isometric knee extension contractions were completed before and after locomotor exercise consisting of eight, 5-min bouts of cycling at 80% of maximum workload. In the control session, subjects completed the isometric contractions in a rested state. Twitch responses to supramaximal motor nerve stimulation and transcranial magnetic stimulation were obtained to assess peripheral force-generating capacity and voluntary activation. Maximum voluntary contraction (MVC) force during brief contractions decreased by 23 +/- 6.3% after cycling exercise and remained 12 +/- 2.8% below baseline 45 min later (F(1,9) > 15.5; P < 0.01). Resting twitch amplitudes declined by approximately 45% (F(1,9) = 28.3; P < 0.001). Cortical voluntary activation declined from 90.6 +/- 1.6% at baseline to 80.6 +/- 2.1% after exercise (F(1,9) = 28.0; P < 0.001) and remained significantly reduced relative to control 30-45 min later (80.6 +/- 3.4%; F(1,9) = 10.7; P < 0.01). Thus locomotor exercise caused a long-lasting impairment in the capacity of the motor cortex to drive the knee extensors. Force was reduced more during sustained MVC after locomotor exercise than in the control session. Peripheral mechanisms contributed relatively more to this force reduction in the control session, whereas supraspinal fatigue played a greater role in sustained MVC reduction after locomotor exercise.

The relationship between monocarboxylate transporters 1 and 4 expression in skeletal muscle and endurance performance in athletes.

The purpose of this study was to examine the relationship between skeletal muscle monocarboxylate transporters 1 and 4 (MCT1 and MCT4) expression, skeletal muscle oxidative capacity and endurance performance in trained cyclists. Ten well-trained cyclists (mean +/- SD; age 24.4 +/- 2.8 years, body mass 73.2 +/- 8.3 kg, VO(2max) 58 +/- 7 ml kg(-1) min(-1)) completed three endurance performance tasks [incremental exercise test to exhaustion, 2 and 10 min time trial (TT)]. In addition, a muscle biopsy sample from the vastus lateralis muscle was analysed for MCT1 and MCT4 expression levels together with the activity of citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD). There was a tendency for VO(2max) and peak power output obtained in the incremental exercise test to be correlated with MCT1 (r = -0.71 to -0.74; P < 0.06), but not MCT4. The average power output (P (average)) in the 2 min TT was significantly correlated with MCT4 (r = -0.74; P < 0.05) and HAD (r = -0.92; P < 0.01). The P (average) in the 10 min TT was only correlated with CS activity (r = 0.68; P < 0.05). These results indicate the relationship between MCT1 and MCT4 as well as cycle TT performance may be influenced by the length and intensity of the task.

Effects of an acute bout of static stretching on 40 m sprint performance: influence of baseline flexibility.

This study investigated the effect of stretching on sprint performance. Ten trained male subjects (age 22 +/- 2.3 yrs; body mass 77.1 +/- 6.9 kg; height 179 +/- 5.5 cm) were randomly assigned to "Rest" and "Stretch" conditions. A low intensity 5 min running warm-up was followed by either 12 min of inactivity (Rest) or lower-limb stretches (Stretch). Subjects walked for 60 s before completing three maximal effort 40 m sprint trials. There were no statistically significant differences in measures of sprint performance between conditions (p > 0.05); however, there was a significant correlation between baseline sit-and-reach scores and mean change in mean velocity between conditions (r = -0.68; p = 0.03). There was a tendency for stretching to negatively effect sprint performance in subjects with comparatively high baseline flexibility. An acute bout of stretching did not exert a significant effect on sprint performance under prescribed conditions.

Training Considerations for Optimising Endurance Development: An Alternate Concurrent Training Perspective.

Whilst the "acute hypothesis" was originally coined to describe the detrimental effects of concurrent training on strength development, similar physiological processes may occur when endurance training adaptations are compromised. There is a growing body of research indicating that typical resistance exercises impair neuromuscular function and endurance performance during periods of resistance training-induced muscle damage. Furthermore, recent evidence suggests that the attenuating effects of resistance training-induced muscle damage on endurance performance are influenced by exercise intensity, exercise mode, exercise sequence, recovery and contraction velocity of resistance training. By understanding the influence that training variables have on the level of resistance training-induced muscle damage and its subsequent attenuating effects on endurance performance, concurrent training programs could be prescribed in such a way that minimises fatigue between modes of training and optimises the quality of endurance training sessions. Therefore, this review will provide considerations for concurrent training prescription for endurance development based on scientific evidence. Furthermore, recommendations will be provided for future research by identifying training variables that may impact on endurance development as a result of concurrent training.