MAOD Determined in a Single Supramaximal Test: a Study on the Reliability and Effects of Supramaximal Intensities.

The main barrier to the wide use of maximal accumulated oxygen deficit (MAOD) is the considerable time required to apply several sub- and supra-maximal exercise sessions. The main question of this study was whether the determination of MAOD using a single supramaximal exercise session (MAODALT) is valid and reliable in running. We investigated the effects of the supramaximal exercise intensity (A) and the reliability of a single supramaximal exercise session (B) to assess MAOD in treadmill running. For this aim 29 subjects participated in A & B studies with single allocation "A" (n=15) and "B" (n=14). The conventional MAOD and 8 MAODALT were determined in exhaustive efforts varying between 100-150% at an intensity associated with maximal oxygen uptake (i+V˙O2MAX). In B study 2 supramaximal efforts were applied to analyze the test-retest reliability. Non-significant differences were found between MAOD and the 8 values of MAODALT. Despite the MAOD being statistically correlated with the MAODALT 100% i+V˙O2MAX (0.490.59), MAODALT determined at 115% of i+V˙O2MAX (52.4±1.7 mL·kg(-1)) presented the higher correlation values (0.650.77) and concordance. In addition, the MAOD at 115% of i+V˙O2MAX presented high test-retest reliability. MAODALT determined at 115% of i+V˙O2MAX was a valid and reliable method to assess MAOD in running.

Metformin improves performance in high-intensity exercise, but not anaerobic capacity in healthy male subjects.

The aim of this study was to determine the ergogenic effects of metformin in high-intensity exercise, as well as its effects on anaerobic capacity, in healthy and physically active men. Ten subjects (mean (± standard deviation) maximal oxygen uptake (V˙O2max ) 38.6 ± 4.5 mL/kg per min) performed the following tests in a cycle ergometer: (i) an incremental test; (ii) six submaximal constant workload tests at 40%-90% (V˙O2max ); and (iii) two supramaximal tests (110% (V˙O2max ). Metformin (500 mg) or placebo was ingested 60 min before the supramaximal test. There were no significant differences between the placebo and metformin groups in terms of maximum accumulated oxygen deficit (2.8 ± 0.6 vs 3.0 ± 0.8 L, respectively; P = 0.08), lactate concentrations (7.8 ± 2.6 vs 7.5 ± 3.0 mmol/L, respectively; P = 0.75) or O2 consumed in either the last 30 s of exercise (40.4 ± 4.4 vs 39.9 ± 4.0 mL/kg per min, respectively; P = 0.35) or the first 110 s of exercise (29.0 ± 2.5 vs 29.5 ± 3.0 mL/kg per min, respectively; P = 0.42). Time to exhaustion was significantly higher after metformin than placebo ingestion (191 ± 33 vs 167 ± 32 s, respectively; P = 0.001). The fast component of V˙O2 recovery was higher in the metformin than placebo group (12.71 vs 12.18 mL/kg per min, respectively; P = 0.025). Metformin improved performance and anaerobic alactic contribution during high-intensity exercise, but had no effect on overall anaerobic capacity in healthy subjects.

Could nanotechnology improve exercise performance? Evidence from animal studies.

This review provides the current state of knowledge regarding the use of nutritional nanocompounds on exercise performance. The reviewed studies used the following nanocompounds: resveratrol-loaded lipid nanoparticles, folic acid into layered hydroxide nanoparticle, redox-active nanoparticles with nitroxide radicals, and iron into liposomes. Most of these nutritional nanocompounds seem to improve performance in endurance exercise compared to the active compound in the non-nanoencapsulated form and/or placebo. Nutritional nanocompounds also induced the following physiological and metabolic alterations: 1) improved antioxidant activity and reduced oxidative stress; 2) reduction in inflammation status; 3) maintenance of muscle integrity; 4) improvement in mitochondrial function and quality; 5) enhanced glucose levels during exercise; 6) higher muscle and hepatic glycogen levels; and 7) increased serum and liver iron content. However, all the reviewed studies were conducted in animals (mice and rats). In conclusion, nutritional nanocompounds are a promising approach to improving exercise performance. As the studies using nutritional nanocompounds were all conducted in animals, further studies in humans are necessary to better understand the application of nutritional nanocompounds in sport and exercise science.

Wearable near-infrared spectroscopy: reliability and sensitivity among different endurance cycling exercise intensities.

The present study investigated the reliability and sensitivity of a wearable near-infrared spectroscopy (wNIRS) device in moderate and heavy exercise intensity domains. On three separate days, eleven males performed an incremental test to exhaustion, and in the following visits, four submaximal constant-load bouts (i.e., test and retest) were performed in the moderate-intensity domain (100 and 130 W) and heavy-intensity domain (160 and 190 W). The local tissue oxygen saturation index (SmO2) and pulmonary oxygen uptake (V̇O2) were measured continuously. The absolute SmO2 and V̇O2 values and the change (Δ) from the 3rd to 6th min of exercise were calculated. There was good reliability for SmO2 measurements, as indicated by the high intraclass correlation coefficient analysis (ICC ≥0.84 for all) and low coefficient of variation between the two trials (CV ≤4.1% for all). Steady-state responses were observed for SmO2 and V̇O2 from the 3rd to the 6th min in the two moderate-intensity bouts (P>0.05), whereas SmO2 decreased and V̇O2 increased from the 3rd to the 6th min in the two heavy-intensity bouts (P<0.05). Together, these findings suggested that the SmO2 measured with a wNIRS device is reliable and sensitive to track local metabolic changes provoked by slight increments in exercise intensity.

Prior exercise reduces fast-start duration and end-spurt magnitude during cycling time-trial.

We examined the pacing strategy and the magnitude of the end spurt during a 200-kJ cycling time trial performed 12-14 h after an exercise protocol designed to reduce muscle glycogen content. 9 physically-active men performed 5 familiarization sessions and 2 experimental 200-kJ time trials in either a control condition (CON) or after an exercise protocol performed the previous evening that was designed to induce muscle glycogen depletion (EP). Mean total time was faster and power output was higher in the CON than in the EP (P<0.01). A fast-start was maintained until the 50-kJ section in CON, but only the 25-kJ section for EP (P<0.05). The power outputs during the 50-, 150- and 200-kJ sections, and the magnitude of the end-spurt, were significantly higher for the CON than for the EP condition (P<0.05). There was no significant difference in the rating of perceived exertion (overall feeling and feeling in legs) between conditions. In conclusion, a protocol designed to decrease muscle glycogen stores reduced the duration of the fast-start and the magnitude of the end spurt during a 200-kJ cycling time trial, impairing the overall performance.

Strength-training with whole-body vibration in long-distance runners: a randomized trial.

A parallel group randomized trial was designed to analyze the impact of 6 weeks of strength training programs performed with or without whole-body vibration on muscular and endurance performance parameters in long-distance runners. 22 endurance runners were allocated into strength with whole-body vibration (n=8), without (n=8), and control (n=6) groups. Before and after the experimental period the subjects performed the following tests: a) maximum dynamic strength test, b) maximal incremental treadmill test, and c) time to exhaustion at velocity corresponding to maximal oxygen uptake. The fractions of the aerobic and anaerobic contribution in time to exhaustion test were also calculated. Both strength trained groups showed a similar increase in maximum dynamic strength (~18%). The aerobic contribution was enhanced for strength training group without whole-body vibration (~25%) after experimental period. No statistical differences were observed in any other variable. These results suggest that 6 weeks of strength training performed with or without whole-body vibration improve similarly the maximum dynamic strength in long-distance runners. In addition, both training modes studied had no deleterious effects on the traditional parameters of endurance performance, traditional strength training program results in increased aerobic contribution during high-intensity aerobic exercise.

Effect of different pacing strategies on 4-km cycling time trial performance.

In cycling, there is a body of evidence that supports that an all-out start strategy is superior to an even-pacing strategy, but it is unknown whether an all-out start strategy is superior to a self-paced strategy. In the present study, we investigated the effects of three different pacing strategies on 4-km cycling time trial performance. After preliminary trials (familiarization trials and a baseline 4-km cycling time trial), in a randomized and counterbalanced order, twelve male cyclists (32.3±7.2 years old, maximum rate of O2 uptake (V̇O2peak) 4.3±0.4 L/min) completed: 1) a self-paced 4-km cycling time trial; 2) an all-out start (∼10 s), followed by maintenance of the average baseline trial power for the first km and self-paced cycling for the remaining trial (all-out+mean); and 3) an all-out start (∼10 s), followed by a power 5% above the average baseline trial power for the first km and self-paced cycling for the remaining trial (all-out+5%mean). Although there was a significant interaction between power and distance (P=0.001) with different power distribution profiles throughout the trial, there was no significant difference (P=0.99) between the three strategies for overall exercise performance (self-paced 379.8±13.9 s, all-out+mean 380.0±16.0 s, and all-out+5%mean 380.2±11.5 s). Oxygen uptake, rating of perceived effort, and heart rate were also similar across the pacing strategies. Different all-out start strategies did not confer additional benefits to performance compared to a self-paced strategy.

Listening to music in the first, but not the last 1.5 km of a 5-km running trial alters pacing strategy and improves performance.

We examined the effects of listening to music on attentional focus, rating of perceived exertion (RPE), pacing strategy and performance during a simulated 5-km running race. 15 participants performed 2 controlled trials to establish their best baseline time, followed by 2 counterbalanced experimental trials during which they listened to music during the first (M start) or the last (M finish) 1.5 km. The mean running velocity during the first 1.5 km was significantly higher in M start than in the fastest control condition (p<0.05), but there was no difference in velocity between conditions during the last 1.5 km (p>0.05). The faster first 1.5 m in M start was accompanied by a reduction in associative thoughts compared with the fastest control condition. There were no significant differences in RPE between conditions (p>0.05). These results suggest that listening to music at the beginning of a trial may draw the attentional focus away from internal sensations of fatigue to thoughts about the external environment. However, along with the reduction in associative thoughts and the increase in running velocity while listening to music, the RPE increased linearly and similarly under all conditions, suggesting that the change in velocity throughout the race may be to maintain the same rate of RPE increase.

Dextrose prolotherapy and corticosteroid injection into rat Achilles tendon.

PURPOSE: To assess the mechanical behavior and the histology of collagen fibers after prolotherapy with 12.5% dextrose into rat Achilles tendons and to compare with those of corticosteroid treatment. METHODS: Out of 60 adult female Wistar rats (70 tendons), 15 received 12.5% dextrose (group I); 15 were treated with corticosteroid injection (group II); and 15 were given 0.9% saline injection (group III), all into the right Achilles tendon, whereas 13 animals received no injections (group IV). Three doses of each substance (groups I, II, and III) were given at a 5-day interval. Collagen fiber color was quantitatively assessed in three samples from each group and in five samples from the control group using picrosirius red staining under polarized and nonpolarized light. Twelve tendons from each group treated with the test substance and 20 tendons from the control group were submitted to the tensile strength test. RESULTS: There was no statistical difference across the groups with respect to maximum load at failure (n.s.) and absorbed energy (n.s.). With respect to tendon rupture, there was no difference between the myotendinous and the tendinous regions (n.s.). However, hematoxylin-eosin staining revealed statistical significance in lymphocytic inflammatory infiltrate (P = 0.008) and in parallel fiber orientation (P = 0.003) when comparing groups to the control group, without significance for either neovascularization (n.s.) or the presence of fibroblasts (n.s.). Likewise, there was no significant difference between the percentage of mature (n.s.) and immature (n.s.) fibers. CONCLUSIONS: Dextrose was not deleterious to the tendinous tissue, as it did not change the mechanical and histological properties of Achilles tendons in rats. The data obtained in this study may help clinicians in their daily work as they suggest that injections of 12.5% dextrose caused no harm to the tendons, although the clinical importance in humans still needs to be defined.

Effects of caffeine on central and peripheral fatigue following closed- and open-loop cycling exercises.

We examined whether endurance performance and neuromuscular fatigue would be affected by caffeine ingestion during closed- and open-loop exercises. Nine cyclists performed a closed-loop (4,000-m cycling time trial) and an open-loop exercise (work rate fixed at mean power of the closed-loop trial) 60 min after ingesting caffeine (CAF, 5 mg/kg) or placebo (PLA, cellulose). Central and peripheral fatigue was quantified via pre- to post-exercise decrease in quadriceps voluntary activation and potentiated twitch force, respectively. Test sensitivity for detecting caffeine-induced improvements in exercise performance was calculated as the mean change in time divided by the error of measurement. Caffeine ingestion reduced the time of the closed-loop trial (PLA: 375.1±14.5 s vs CAF: 368.2±14.9 s, P=0.024) and increased exercise tolerance during the open-loop trial (PLA: 418.2±99.5 s vs CAF: 552.5±106.5 s, P=0.001), with similar calculated sensitivity indices (1.5, 90%CI: 0.7-2.9 vs 2.8, 90%CI: 1.9-5.1). The reduction in voluntary activation was more pronounced (P=0.019) in open- (-6.8±8.3%) than in closed-loop exercises (-1.9±4.4%), but there was no difference between open- and closed-loop exercises for the potentiated twitch force reduction (-25.6±12.8 vs -26.6±12.0%, P>0.05). Caffeine had no effect on central and peripheral fatigue development in either mode of exercise. In conclusion, caffeine improved endurance performance in both modes of exercise without influence on post-exercise central and peripheral fatigue, with the open-loop exercise imposing a greater challenge to central fatigue tolerance.

Cardiopulmonary, blood metabolite and rating of perceived exertion responses to constant exercises performed at different intensities until exhaustion.

OBJECTIVE: This study analysed cardiopulmonary, metabolic and rating of perceived exertion (RPE) responses during exercise bouts performed below, at and above the second lactate threshold (LT2) intensity. METHODS: 10 healthy men performed constant workloads to exhaustion at the first lactate threshold (LT1), LT2 and 25% of the difference between LT2 and maximal aerobic power output (TW(25%)) identified during an incremental test. The time to exhaustion (TE) was 93.8 (18.0), 44.5 (16.0) and 22.8 (10.6) min at LT1, LT2 and TW(25%), respectively (p < 0.001). Metabolic and cardiopulmonary parameters and RPE data were time normalised to the exercise bout duration. The correlation between the slope of these variables and TE was calculated. RESULTS: Differences were found for respiratory exchange ratio (RER), RPE and potassium at LT1; RER, RPE, norepinephrine and potassium at LT2; and ventilation, respiratory rate (RR), RPE, lactate and potassium at TW(25%). Except for RR, no cardiopulmonary or metabolic parameter increased significantly after 50% of the exercise duration, indicating a physiological steady state. VO2, heart rate and lactate at exhaustion in all exercise bouts were significantly lower than values reached in the maximal incremental test. The slope of most metabolic variables was not correlated to TE in LT1, LT2 and TW(25%), whereas the slope of RPE was significantly correlated to TE (r = -0.72 to -0.84; p < 0.05) for the three exercise intensities. CONCLUSION: Contrary to traditional suggestions, exercise at LT1, LT2 and TW(25%) intensities is performed and terminated in the presence of an overall physiological steady state.

Aerobic profile of climbers during maximal arm test.

This study compared measurements of upper body aerobic fitness in elite (EC; n=7) and intermediate rock climbers (IC; n=7), and a control group (C; n=7). Subjects underwent an upper limb incremental test on hand cycle ergometer, with increments of 23 W · min(-1), until exhaustion. Ventilation (VE) data were smoothed to 10 s averages and plotted against time for the visual determination of the first (VT1) and second (VT2) ventilatory thresholds. Peak power output was not different among groups [EC=130.9 (±11.8) W; IC=122.1 (±28.4) W; C=115.4 (±15.1) W], but time to exhaustion was significantly higher in EC than IC and C. VO(2 PEAK) was significantly higher in EC [36.8 (±5.7) mL.kg(-1).min(-1)] and IC [35.5 (±5.2) mL.kg(-1).min(-1)] than C [28.8 (±5.0) mL.kg(-1).min(-1)], but there was no difference between EC and IC. VT1 was significantly higher in EC than C [EC=69.0 (±9.4) W; IC=62.4 (±13.0) W; C=52.1 (±11.8) W], but no significant difference was observed in VT2 [EC=103.5 (±18.8) W; IC=92.0 (±22.0) W; C=85.6 (±19.7) W]. These results show that elite indoor rock climbers elicit higher aerobic fitness profile than control subjects when measured with an upper body test.

Caffeine intake reduces sedentary time and increases physical activity predisposition in obese police officers.

Sedentary time is associated with increased obesity in police officers. Caffeine intake may reduce sedentary time but it has not been extensively investigated. In the present study, the effect of caffeine ingestion on sedentary time was investigated in obese police officers. Fourteen obese police officers ingested either 5 mg/kg of caffeine or cellulose (placebo) for six days. Information on inactivity time, time spent with physical activities, self-reported perception of tiredness, and physical activity disposition was obtained daily during the intervention period. Sedentary and physical activity times were divided into two intraday periods (T1: 08:00 am-02:00 pm and T2: 02:00 pm-08:00 pm). Caffeine intake decreased the sedentary time in both T1 (79.2±2.2%) and T2 (79.1±2.5%), when compared with T2 of the placebo condition (81.1±3.6%, P<0.05). Caffeine intake also increased the time spent on light physical activities in T1 and T2 (17±2 and 18±2%), when compared with T2 of the placebo condition (16±3%, P<0.05). In addition, sedentary time increased and light physical activity time decreased from T1 to T2 in the placebo (P<0.001) but not in the caffeine condition (P=0.81). Caffeine intake had no effect on tiredness (P>0.05), but it increased the self-reported physical activity disposition compared to the placebo condition (4.5±2.7 vs 3.2±2.3 units, P<0.05). Caffeine intake reduced the sedentary time and increased the time spent on light physical activities of obese police officers, which seems to be related to a higher disposition for the practice of physical activity.

Caffeine ingestion improves specific artistic swimming tasks.

The main movements of artistic swimming demand various physical capacities such as flexibility, strength, power, and muscular endurance. The use of ergogenic resources to potentialize performance in this sport, however, is underexplored and deserves investigation. In the present study, we tested whether caffeine ingestion would improve the execution of movements that are essential in a typical figure competition or routines in artistic swimming (i.e., amplitude in the Ariana, height in the Boost and Barracuda, and time maintained in the Stationary Scull techniques). Sixteen experienced female athlete artistic swimmers (17.4±3.2 years of age, 5.6±2.8 years of artistic swimming practice) performed several movements of artistic swimming after having ingested a capsule containing caffeine (5 mg/kg body mass) or cellulose (placebo). Compared to the placebo, caffeine improved latero-lateral amplitude during the Ariana (P=0.035), the height of the Boost and Barracuda (P=0.028 and 0.009), and maintained duration in Stationary Sculling (P=0.012). Bayes factor analysis, however, indicated substantial evidence of a positive effect of caffeine only on the Barracuda and Stationary Scull techniques. These findings indicated that caffeine improved performance during specific artistic swimming movements. Coaches and athletes should consider caffeine ingestion in their supplementation plans.

Footwear designed to enhance energy return improves running economy compared to a minimalist footwear: does it matter for running performance?

The present study compared the effects of a footwear designed to enhance energy return (thermoplastic polyurethane, TPU) vs minimalist shoes on running economy (RE) and endurance performance. In this counterbalanced and crossover design study, 11 recreational male runners performed two submaximal constant-speed running tests and two 3-km time-trials with the two shoe models. Oxygen uptake was measured during submaximal constant-speed running tests in order to determine the RE at 12 km/h and oxygen cost of running (CTO2) at individual average speed sustained during the 3-km running time-trials wearing either of the two shoes. Our results revealed that RE was improved (2.4%) with TPU shoes compared with minimalist shoes (P=0.01). However, there was no significant difference for CTO2 (P=0.61) and running performance (P=0.52) comparing the TPU (710±60 s) and the minimalist (718±63 s) shoe models. These novel findings demonstrate that shoes with enhanced mechanical energy return (i.e. TPU) produced a lower energy cost of running at low (i.e., 12 km/h) but not at high speeds (i.e., average speed sustained during the 3-km running time-trial, ∼15 km/h), ultimately resulting in similar running performance compared to the minimalist shoe.

Predicting MAOD using only a supramaximal exhaustive test.

The objective of this study was to propose an alternative method (MAOD(ALT)) to estimate the maximal accumulated oxygen deficit (MAOD) using only one supramaximal exhaustive test. Nine participants performed the following tests: (a) a maximal incremental exercise test, (b) six submaximal constant workload tests, and (c) a supramaximal constant workload test. Traditional MAOD was determined by calculating the difference between predicted O(2) demand and accumulated O(2) uptake during the supramaximal test. MAOD(ALT) was established by summing the fast component of excess post-exercise oxygen consumption and the O(2) equivalent for energy provided by blood lactate accumulation, both of which were measured during the supramaximal test. There was no significant difference between MAOD (2.82+/-0.45 L) and MAOD(ALT) (2.77+/-0.37 L) (P=0.60). The correlation between MAOD and MAOD(ALT) was also high (r=0.78; P=0.014). These data indicate that the MAOD(ALT) can be used to estimate the MAOD.

Could nanotechnology improve exercise performance? Evidence from animal studies

Abstract This review provides the current state of knowledge regarding the use of nutritional nanocompounds on exercise performance. The reviewed studies used the following nanocompounds: resveratrol-loaded lipid nanoparticles, folic acid into layered hydroxide nanoparticle, redox-active nanoparticles with nitroxide radicals, and iron into liposomes. Most of these nutritional nanocompounds seem to improve performance in endurance exercise compared to the active compound in the non-nanoencapsulated form and/or placebo. Nutritional nanocompounds also induced the following physiological and metabolic alterations: 1) improved antioxidant activity and reduced oxidative stress; 2) reduction in inflammation status; 3) maintenance of muscle integrity; 4) improvement in mitochondrial function and quality; 5) enhanced glucose levels during exercise; 6) higher muscle and hepatic glycogen levels; and 7) increased serum and liver iron content. However, all the reviewed studies were conducted in animals (mice and rats). In conclusion, nutritional nanocompounds are a promising approach to improving exercise performance. As the studies using nutritional nanocompounds were all conducted in animals, further studies in humans are necessary to better understand the application of nutritional nanocompounds in sport and exercise science.

Wearable near-infrared spectroscopy: reliability and sensitivity among different endurance cycling exercise intensities

The present study investigated the reliability and sensitivity of a wearable near-infrared spectroscopy (wNIRS) device in moderate and heavy exercise intensity domains. On three separate days, eleven males performed an incremental test to exhaustion, and in the following visits, four submaximal constant-load bouts (i.e., test and retest) were performed in the moderate-intensity domain (100 and 130 W) and heavy-intensity domain (160 and 190 W). The local tissue oxygen saturation index (SmO2) and pulmonary oxygen uptake (V̇O2) were measured continuously. The absolute SmO2 and V̇O2 values and the change (Δ) from the 3rd to 6th min of exercise were calculated. There was good reliability for SmO2 measurements, as indicated by the high intraclass correlation coefficient analysis (ICC ≥0.84 for all) and low coefficient of variation between the two trials (CV ≤4.1% for all). Steady-state responses were observed for SmO2 and V̇O2 from the 3rd to the 6th min in the two moderate-intensity bouts (P>0.05), whereas SmO2 decreased and V̇O2 increased from the 3rd to the 6th min in the two heavy-intensity bouts (P<0.05). Together, these findings suggested that the SmO2 measured with a wNIRS device is reliable and sensitive to track local metabolic changes provoked by slight increments in exercise intensity.

Does caffeine ingestion before a short-term sprint interval training promote body fat loss?

We investigated the effect of caffeine ingestion combined with a 2-wk sprint interval training (SIT) on training-induced reductions in body adiposity. Twenty physically-active men ingested either 5 mg/kg of cellulose as a placebo (PLA, n=10) or 5 mg/kg of caffeine (CAF, n=10) 60 min before each SIT session (13×30 s sprint/15 s of rest). Body mass and skinfold thickness were measured pre- and post-training. Energy expenditure was measured at rest, during exercise, and 45 min after exercise in the first SIT session. Body fat was similar between PLA and CAF groups at pre-training (P>0.05). However, there was a significant decrease in body fat after training in the CAF group (-5.9±4.2%, P<0.05) but not in PLA (1.5±8.0%, P>0.05). There was no difference in energy expenditure at rest and during exercise between PLA and CAF groups (P>0.05), but the post-exercise energy expenditure was 18.3±21.4% greater in the CAF than in the PLA group (P<0.05). In conclusion, caffeine ingestion before SIT sessions induced a body fat loss that may be associated with higher post-exercise energy expenditure.