Maximal Cycling Power Research Articles

Inhalation of Hydrogen-rich Gas before Acute Exercise Alleviates Exercise Fatigue: A Randomized Crossover Study.

Hydrogen, as an antioxidant, may have the potential to mitigate fatigue and improve selected oxidative stress markers induced by strenuous exercise. This study focused on a previously unexplored approach involving pre-exercise inhalation of hydrogen-rich gas (HRG). Twenty-four healthy adult men first completed pre-laboratories to determine maximum cycling power (Wmax) and maximum cycling time (Tmax). Then they were subjected to ride Tmax at 80% Wmax and 60-70 rpm on cycle ergometers after inhaled HRG or placebo gas (air) for 60-minute in a double-blind, counterbalanced, randomized, and crossover design. The cycling frequency in the fatigue modeling process and the rating of perceived exertion (RPE) at the beginning and end of the ride were recorded. Before gas inhalation and after fatigue modeling, visual analog scale (VAS) for fatigue and counter-movement jump (CMJ) were tested, and blood samples were obtained. The results showed that compared to a placebo, HRG inhalation induced significant improvement in VAS, RPE, the cycling frequency during the last 30 seconds in the fatigue modeling process, the ability to inhibit hydroxyl radicals, and serum lactate after exercise (p<0.028), but not in CMJ height and glutathione peroxidase activity. The cycling frequency during the last 30 seconds of all other segments in the fatigue modeling process was within the range of 60-70 rpm. In conclusion, HRG inhalation prior to acute exercise can alleviate exercise-induced fatigue, maintain functional performance, and improve hydroxyl radical and lactate levels.

Feasibility and early effects of bed-cycling eccentric training: Potential clinical applications.

This study aimed to evaluate feasibility and early effects of moderate intensity bed-cycling eccentric training on healthy individuals, and establish whether this training modality could be implemented into bedridden patients'routine care. Longitudinal study with prepost exercise intervention measurements. The development of a bed-adapted eccentric ergometer allowed to conduct five training sessions during 3 weeks at increasing intensity on 11 healthy individuals. Force-speed relationship, maximal voluntary knee extension force and neural activation of subjects were evaluated before and after the programme. Five training sessions were sufficient to decrease the rate of perceived exertion whereas eccentric power output increased (+40%). After training, maximal voluntary isometric contraction force measured during knee extension had significantly improved in all subjects, with a mean increase of 17%. Maximal cycling power was also significantly higher (+7%) after the training programme. Taken together, these results show that moderate load eccentric bed cycling (i) was feasible and efficient, (ii) did not generate excessive individual perception of effort during exercise nor develop major muscular or joint pain after training and (iii) allowed early force and power gains in healthy subjects.

Effect of Six-Week Speed Endurance Training on Peripheral Fatigue.

(1) Speed endurance training (inducing a high blood lactate concentration) delays excitation–contraction coupling impairment, thus providing more space for high-frequency fatigue to occur in the early stage of maximal concentric actions. This study aimed to test the hypothesis that the maintenance type of speed endurance training may shift peripheral fatigue from low-frequency to high-frequency fatigue after the 15 s long Wingate test. (2) Six students of physical education performed the corresponding training for six weeks. Before and after this period, they were tested for low- and high-frequency fatigue after the 15 s long Wingate test; additionally, their blood lactate concentrations, maximal cycling power, work, fatigue index, and muscle twitch responses were also tested. (3) The training increased the maximal cycling power and work (p < 0.001 and p < 0.01, respectively) with minor changes in the mean fatigue index and blood lactate concentration (both p > 0.05). Low-frequency dominant fatigue before the training showed a trend toward high-frequency dominant fatigue after the training (p > 0.05). (4) The results showed that the 15 s Wingate test failed to induce significant high-frequency fatigue. Even though it displayed a substantial fatigue index, the changes in favor of high-frequency fatigue were too small to be relevant.

Great power comes at a high (locomotor) cost: the role of muscle fascicle length in the power versus economy performance trade-off.

Muscle design constraints preclude simultaneous specialization of the vertebrate locomotor system for explosive and economical force generation. The resulting performance trade-off between power and economy has been attributed primarily to individual differences in muscle fiber type composition. While certainly crucial for performance specialization, fiber type likely interacts with muscle architectural parameters, such as fascicle length, to produce this trade-off. Longer fascicles composed of more serial sarcomeres can achieve faster shortening velocities, allowing for greater power production. Long fascicles likely reduce economy, however, because more energy-consuming contractile units are activated for a given force production. We hypothesized that longer fascicles are associated with both increased power production and locomotor cost. In 11 power-trained and 13 endurance-trained recreational athletes, we measured (1) muscle fascicle length via ultrasound in the gastrocnemius lateralis, gastrocnemius medialis and vastus lateralis, (2) maximal power during cycling and countermovement jumps, and (3) running cost of transport. We estimated muscle fiber type non-invasively based on the pedaling rate at which maximal cycling power occurred. As predicted, longer gastrocnemius muscle fascicles were correlated with greater lower-body power production and cost of transport. Multiple regression analyses revealed that variability in maximal power was explained by fiber type (46% for cycling, 24% for jumping) and average fascicle length (20% for cycling, 13% for jumping), while average fascicle length accounted for 15% of the variation in cost of transport. These results suggest that, at least for certain muscles, fascicle length plays an important role in the power versus economy performance trade-off.

Concurrent endurance and resistance training enhances muscular adaptations in individuals with metabolic syndrome.

The purpose of the study was to determine if concurrent training (endurance and resistance in a single session) elicits leg muscular adaptations beyond the ones obtained by endurance training alone in sedentary individuals with metabolic syndrome (MetS). Sixty-six MetS individuals (37% women, age 56±7years, BMI 32±5kgm-2 and 3.8±0.8 MetS factors) were randomized to undergo one of the following 16-week isocaloric exercise programs: (i) 4+1 bouts of 4min at 90% of HRMAX of intense aerobic cycling (IAC+IAC group; n=33), (ii) 4 IAC bouts followed by 3 sets of 12 repetitions of 3 lower-limb free-weight exercises (IAC+RT group; n=33). We measured the effects of training on maximal cycling power, leg press maximum strength (1RM), countermovement jump height (CMJ), and mean propulsive velocity (MPV) at workloads ranging from 10% to 100% of baseline 1RM leg press. After intervention, MetS components (Z-score) improved similarly in both groups (p=0.002). Likewise, maximal cycling power during a ramp test improved similarly in both groups (time effect p<0.001). However, leg press 1RM improved more in IAC+RT than in IAC+IAC (47±5 vs 13±5kg, respectively, interaction p<0.001). CMJ only improved with IAC+RT (0.8±0.2cm, p=0.001). Leg press MPV at heavy loads (ie, 80%-100% 1RM) improved more with concurrent training (0.12±0.01 vs 0.06±0.02ms-1 , interaction p=0.013). In conclusion, in unconditioned MetS individuals, intense aerobic cycling alone improves leg muscle performance. However, substituting 20% of intense aerobic cycling by resistance training further improves 1RM leg press, MPV at high loads, and jumping ability while providing similar improvement in MetS components.

Effects of high-intensity interval training combined with traditional strength or power training on functionality and physical fitness in healthy older men: A randomized controlled trial.

Concurrent training (CT) is an efficient strategy to improve neuromuscular function and cardiorespiratory fitness in older adults, which are factors of pivotal importance for the maintenance of functional capacity with aging. However, there is a lack of evidence about the effectiveness of power training (PT) as an alternative to traditional strength training (TST) during CT. Thus, the aim of the present study was to examine the effect of 16weeks (twice weekly) TST combined with high intensity interval training (TST+HIIT) vs. PT combined with HIIT (PT+HIIT) on functional performance, cardiorespiratory fitness and body composition in older men. Thirty five older men (65.8±3.9years) were randomly allocated into two training groups: TST+HIIT (n=18), and PT+HIIT (n=17). TST+HIIT performed resistance training at intensities ranging from 65% to 80% 1RM at slow controlled speed (≅ 2s for each concentric phase), whereas PT+HIIT trained at intensities ranging from 40% to 60% of 1RM at maximal intentional speed. Both groups performed HIIT at intensities ranging from 75 to 90% of VO2peak. Participants performed functional tests (sit-to-stand, timed-up-and-go, stair climbing); cardiopulmonary exercise testing (maximal cycling power output: Wmax, peak oxygen uptake: VO2peak, cycling economy), as well as body composition assessment (DXA) before, post 8 and post 16weeks of training. The groups improved similarly (P<0.05) with training in all functional capacity outcomes, Wmax, cycling economy, VO2peak and body composition (P<0.05). These findings suggest that HIIT based CT programs involving TST vs. PT are equally effective in improving functionality, cardiorespiratory fitness and body composition in healthy older men.

Power Reserve at Intolerance in Ramp-Incremental Exercise Is Dependent on Incrementation Rate.

The mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown. In twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min-1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout. Baseline Piso was not different among RI rates (analysis of variance; P > 0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P < 0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P > 0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P < 0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P < 0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P > 0.05), thus there was no "power reserve." In RI-10, Piso was greater than RI peak power at intolerance (P < 0.001), that is, there was a "power reserve." In RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.

Thermodynamic analysis and parametric optimization of a novel S–CO2 power cycle for the waste heat recovery of internal combustion engines

With the aim to recover the exhaust heat of internal combustion engine efficiently, a novel supercritical CO2 (S–CO2) power cycle is proposed on the basis of recompression cycle configuration. The corresponding thermodynamic models are established to analyze the energetic and exergetic performances of the system. The effects of turbine inlet temperatures and system pressures are investigated. Thereafter, in order to output the maximum net work, genetic algorithm (GA) is employed to optimize these key parameters. Under design conditions, the calculated results indicate that the thermal efficiency and the exergy efficiency of the system can reach up to 35.86% and 67.90% respectively. Furthermore, as the inlet temperature of high pressure turbine increases, cycle efficiency increases while output work decreases. However, for the effect of inlet temperature of low pressure turbine, cycle efficiency and output work increase with the increase of temperature. As for the intermediate pressure of this system, there exist pressures to get the maximum net work and cycle efficiency. Based on GA optimization, an optimal combination of system parameters is obtained. The corresponding maximum cycle power is 39.49 kW, and the recovery efficiency of waste heat can reach up to 74.83%.

Vibrotactile Feedback During Physical Exercise: Perception of Vibrotactile Cues in Cycling.

The aim of this study was to investigate the perception of vibrotactile signals during physical exercise by comparing differences in recognition between stationary and cycling positions. The impact of physical exercise on the ability to perceive vibrotactile cues is unknown, whereas the recognition in stationary position has been shown previously. Vibrating elements were positioned at 3 locations on the thighs and spine of 9 athletes to apply various vibrotactile cues. Subjects performed at 0, 50, 70 and 90% of their maximal cycling power output and denoted the interpretation of the vibration signals on a touchscreen. The results show a similarity in correct recognition between stationary position and physical exercise for the thighs and spine (p>0.1) and demonstrate a decrease in response time for 70 and 90% levels of physical exercise compared to 0 and 50% (p<0.001). Furthermore, vibrotactile signals at the spine are noticed more accurately and more rapidly compared to the thighs (p<0.01). These results suggest that vibrotactile feedback also has potential in applications during physical exercise. The potential use of vibrotactile feedback can be in cycling for, among other, correcting the aerodynamic position. Applications in other sports and health-related domains are feasible as well.

Energy expenditure of household activities and cardiorespiratory fitness in women with obesity.

SummaryPatients with obesity experience difficulties in executing household activities. Our purpose was to compare the energy expenditure and exercise intensity of daily household activities and cardiorespiratory fitness (CRF) in women with obesity and normal weight women. Twenty‐eight non‐obese women (NO, 44.6 ± 7.2 years; body mass index [BMI] 22.1 ± 1.7 kg m−2) and 20 women with obesity (OB, 44.0 ± 7.7 years; BMI 33.4 ± 2.7 kg.m−2). Peak oxygen uptake (⩒O2peak), maximal heart rate (HR) and maximal cycling power output were measured during a maximal incremental cycling test to assess CRF. Oxygen uptake (⩒O2) used to assess CRF was measured during a standardized protocol that included ironing, cleaning floor and walking and climbing stairs. The intensity of the three household activities was expressed by the ratio between ⩒O2 during household activity (⩒O2‐activity) and resting ⩒O2, and between ⩒O2 during household activity and ⩒O2peak. ⩒O2 peak was higher in OB (1845.2 ± 290.5 mL min−1) than in NO women (1612.6 ± 250.9 mL min−1, P &lt; 0.01). There were no significant differences for the ratio between ⩒O2‐activity and resting ⩒O2 between NO and OB women for any of the three household activities. No differences were observed either between the two groups for the ratio of ⩒O2‐activity to ⩒O2peak. In healthy women with obesity and normal CRF, physical activity (PA) may not be affected by energy need and intensity of household activities. In this way, these women can be motivated to maintain a high PA level contributing to lessen the cardiovascular risk.

The cardinal exercise stopper: Muscle fatigue, muscle pain or perception of effort?

The capacity to sustain high-intensity aerobic exercise is essential for endurance performance. Therefore, it is important to understand what is the factor limiting time to exhaustion (TTE) in healthy and fit adults. In Study 1, maximal voluntary cycling power (MVCP) was measured in 11 volunteers before and immediately after a high-intensity TTE test on cycle ergometer. Cadence was 60 rpm in both the MVCP and TTE tests. Despite a 35% loss in MVCP, power produced during the final MVCP test (mean ± SD 469 ± 111 W) was significantly higher than the power required by the TTE test (269 ± 55 W) (P < 0.001). In Study 2, 12 participants performed a cold pressor test (CPT) to the limit of tolerance followed by a high-intensity TTE test on cycle ergometer. Ratings of pain unpleasantness (RPU) during the TTE test were anchored to the unpleasantness of pain experienced during the CPT. On average, the RPU was 9.7 ± 0.4 at completion of the CPT and 5.0 ± 0.9 at exhaustion during the TTE test. The difference between these two ratings of pain unpleasantness was statistically significant (P < 0.001). In both Studies 1 and 2, the slope of the rating of perceived exertion (RPE) during the TTE test correlated significantly with TTE (r = -0.75 and -0.83, P < 0.01). Results of this two-part investigation suggest that perception of effort, rather than severe locomotor muscle fatigue or intolerably unpleasant muscle pain, is the cardinal exercise stopper during high-intensity aerobic exercise.

Simulated work loops predict maximal human cycling power.

Fish, birds and lizards sometimes perform locomotor activities with maximized muscle power. Whether humans maximize muscle power is unknown because current experimental techniques cannot be applied non-invasively. This study leveraged simulated muscle work loops to examine whether voluntary maximal cycling is characterized by maximized muscle power. The simulated work loops used experimentally measured joint angles, anatomically realistic muscle parameters (muscle-tendon lengths, velocities and moment arms) and a published muscle model to calculate power and force for 38 muscles. For each muscle, stimulation onset and offset were optimized to maximize muscle work and power for the complete shortening/lengthening cycle. Simulated joint power and total leg power (i.e. summed muscle power) were compared with previously reported experimental joint and leg power. Experimental power values were closely approximated by simulated maximal power for the leg [intraclass correlation coefficient (ICC)=0.91], the hip (ICC=0.92) and the knee (ICC=0.95), but less closely for the ankle (ICC=0.74). Thus, during maximal cycling, humans maximize muscle power at the hip and knee, but the ankle acts to transfer (instead of maximize) power. Given that only the timing of muscle stimulation onset and offset were altered, these results suggest that human motor control strategies may optimize muscle activation to maximize power. The simulations also provide insight into biarticular muscle function by demonstrating that the power values at each joint spanned by a biarticular muscle can be substantially greater than the net power produced by the muscle. Our work-loop simulation technique may be useful for examining clinical deficits in muscle power production.

Noncircular Chainrings Do Not Influence Maximum Cycling Power.

Noncircular chainrings could increase cycling power by prolonging the powerful leg extension/flexion phases, and curtailing the low-power transition phases. We compared maximal cycling power-pedaling rate relationships, and joint-specific kinematics and powers across 3 chainring eccentricities (CON = 1.0; LOWecc = 1.13; HIGHecc = 1.24). Part I: Thirteen cyclists performed maximal inertial-load cycling under 3 chainring conditions. Maximum cycling power and optimal pedaling rate were determined. Part II: Ten cyclists performed maximal isokinetic cycling (120rpm) under the same 3 chainring conditions. Pedal and joint-specific powers were determined using pedal forces and limb kinematics. Neither maximal cycling power nor optimal pedaling rate differed across chainring conditions (all p > .05). Peak ankle angular velocity for HIGHecc was less than CON (p < .05), while knee and hip angular velocities were unaffected. Self-selected ankle joint-center trajectory was more eccentric than HIGHecc with an opposite orientation that increased velocity during extension/flexion and reduced velocity during transitions. Joint-specific powers did not differ across chainring conditions, with a small increase in power absorbed during ankle dorsiflexion with HIGHecc. Multiple degrees of freedom in the leg, crank, and pedal system allowed cyclists to manipulate ankle angular velocity to maintain their preferred knee and hip actions, suggesting maximizing extension/flexion and minimizing transition phases may be counterproductive for maximal power.

Factors contributing to lower metabolic demand of eccentric compared with concentric cycling.

This study compared muscle-tendon behavior, muscle oxygenation, and muscle activity between eccentric and concentric cycling exercise at the same work output to investigate why metabolic demand is lower during eccentric cycling than with concentric cycling. Eleven untrained men (27.1 ± 7.0 y) performed concentric cycling (CONC) and eccentric cycling (ECC) for 10 min (60 rpm) at 65% of the maximal concentric cycling power output (191 ± 45 W) 4 wk apart. During cycling, oxygen consumption (V̇o2), heart rate (HR), vastus lateralis (VL) tissue total hemoglobin (tHb), and oxygenation index (TOI) were recorded, and muscle-tendon behavior was assessed using ultrasonography. The surface electromyogram (EMG) was recorded from VL, vastus medialis (VM), rectus femoris (RF), and biceps femoris (BF) muscles, and cycling torque and knee joint angle during each revolution were also recorded. Average V̇o2 (-65 ± 7%) and HR (-35 ± 9%) were lower and average TOI was greater (16 ± 1%) during ECC than CONC, but tHb was similar between bouts. Positive and negative cycling peak crank torques were greater (32 ± 21 and 48 ± 24%, respectively) during ECC than CONC, but muscle-tendon unit and fascicle and tendinous tissue length changes during pedal revolutions were similar between CONC and ECC. VL, VM, RF, and BF peak EMG amplitudes were smaller (24 ± 15, 22 ± 18, 16 ± 17, and 18 ± 9%, respectively) during ECC than CONC. These results suggest that the lower metabolic cost of eccentric compared with concentric cycling was due mainly to a lower level of muscle activation per torque output.NEW & NOTEWORTHY This study shows that lower oxygen consumption of eccentric compared with concentric cycling at the same workload is explained by lower muscle activity of agonist and antagonist muscles during eccentric compared with during concentric cycling.

High Intensity Interval Training Changes Skeletal Muscle Insulin Signalling Pathway Of Obese Individuals

PURPOSE: Obesity, characterized as excess of body fat (BMI ≥ 30 kg•m-2), is related to the development of various metabolic disorders, including insulin resistance. Exercise is known to serve as a non-pharmacological approach to increase skeletal muscle insulin sensitivity, although the mechanisms have not been fully elucidated. Additionally, the molecular underpinnings of the effects of high intensity interval training (HIIT) on insulin resistance are less understood. This study evaluated the effects of HIIT on biochemical and molecular markers related to insulin resistance in physically inactive obese individuals. METHODS: 9 obese insulin sensitive (OB; 32 ± 10 y; 92.4 ± 12.9 kg; 35.1 ± 3.8 kg•m-2) and 8 obese insulin resistant (OBR; 30 ± 11 y; 106.0 ± 19.6 kg; 37.8 ± 4.6 kg•m-2) volunteers were subjected to 8 weeks of HIIT using a cycle ergometer. Insulin resistance was defined as homeostasis model assessment index (HOMA-IR) equal or greater than 2.71. Before and after the training, a maximal ramp test was performed to measure maximal cycling power output. HIIT was performed 3 times a week with progressively increasing intensity and volume (8 to 12 bouts of 1 min duration at 80 to 110% of the maximum power output separated by 1 min active recovery at 30 W). A muscle biopsy and venous blood were performed 72 hours before and after HIIT to allow HOMA-IR calculation. Skeletal muscle samples were analyzed by Western Blot. RESULTS: HIIT increased insulin sensitivity evaluated by HOMA-IR in OBR (4.4 ± 1.4 versus 4.1 ± 2.2, p=0.02) but not in OB (1.8 ± 0.5 versus 2.3 ± 1.0) volunteers. In skeletal muscle, HIIT increased phosphorylation of the insulin receptor substrate (Tyr612), Protein kinase B (AKT Ser473) and protein kinase dependent calcium/calmodulin (CaMKII) (Thr286), and increased expression of β-hydroxyacyl-CoA dehydrogenase (β-HAD), and cytochrome C oxidase (COX-IV). There was also a reduction of phosphorylation of extracellular signal regulated kinase (ERK1/2) in OBR. CONCLUSIONS: 8 weeks of HIIT promoted improvements in insulin sensitivity, modified components of insulin signaling pathway, and improved oxidative metabolism in skeletal muscle. These changes were independent of changes in body fat. This work was supported by CAPES (PNPD-2455/2011), FAPEMIG (CDS APQ01621-10), and CNPq (477154/2011-5) grants.

DHA-rich Fish Oil Increases the Omega-3 Index and Lowers the Oxygen Cost of Physiologically Stressful Cycling in Trained Individuals.

Dietary fish oil, providing docosahexaenoic acid (DHA) modulates oxygen consumption and fatigue in animal models. However, in humans predominately supplemented with high eicosapentaenoic acid (EPA), there is no evidence of endurance performance enhancement. Therefore, this study examined if DHA-rich fish oil could improve repeated bouts of physiologically stressful cycling and a subsequent time trial in a state of fatigue. Twenty-six trained males took part in a double-blind study and were supplemented with either 2 × 1g/day soy oil, Control) or DHA-rich tuna fish oil (Nu-Mega) (FO) (560mg DHA / 140mg eicosapentaenoic acid (EPA), for 8 weeks. Maximal cycling power (3 × 6s), isometric quadriceps strength (MVC), Wingate cycling protocol (6 × 30s) and a 5min cycling time-trial were assessed at baseline and eight weeks. The Omega-3 Index was not different at baseline (Control: 4.2 ± 0.2; FO: 4.7 ± 0.2%) and increased in the FO group after eight weeks (Control: 3.9 ± 0.2; FO: 6.3 ± 0.3%, p < .01). There was no effect of DHA-rich fish oil on power output of maximal 6s cycle sprinting (Control: Pre 1100 ± 49 Post 1067 ± 51; FO: Pre 1070 ± 46 Post 1042 ± 46W), during 5min time trail (Control: Pre 267 ± 19 Post 278 ± 20; FO: Pre 253 ± 16 Post 265 ± 16 W) or maximal voluntary contraction force (Control: Pre 273 ± 19 Post 251 ± 19; FO: Pre 287 ± 17 Post 283 ± 16 Nm). Nevertheless, relative oxygen consumption was reduced the FO group during the cycling time trial (Control: -23 ± 26; FO: -154 ± 59ml O2/min/100W p < .05) suggesting improved economy of cycling. We conclude that DHA-rich fish oil, successful at elevating the Omega-3 Index, and reflective of skeletal muscle membrane incorporation, can modulate oxygen consumption during intense exercise.

Increase in Maximal Cycling Power With Acute Dietary Nitrate Supplementation.

This study determined whether NO3- supplementation could acutely enhance maximal power in trained athletes. In this double-blind, crossover study, 13 trained athletes performed maximal inertial-load cycling trials (3-4 s) immediately before (PRE) and after (POST) consuming either NO3-rich (NO3) or NO3-depleted (PLA) BRJ to assess acute changes (ie, within the same day) in maximal power (PMAX) and optimal pedaling rate (RPMopt). Participants also performed maximal isokinetic cycling (30 s) to assess performance differences after supplementation. 2 x 2 repeated-measures ANOVA indicated a greater increase in PMAX from PRE to POST NO3 (PRE 1160 ± 301 W to POST 1229 ± 317 W) than with PLA (PRE 1191 ± 298 W to POST 1213 ± 300 W) (P = .009; ηp2 = 0.45). A paired t-test verified a greater relative change in PMAX after NO3 (6.0% ± 2.6%) than with PLA (2.0% ± 3.8%) (P = .014; d = 1.21). RPMopt remained unchanged from PRE (123 ± 14 rpm) to POST PLA (122 ± 14 rpm) but increased from PRE (120 ± 14 rpm) to POST NO3 (127 ± 13 rpm) (P = .043; ηp2 = 0.30). There was no relative change in RPMopt after PLA (-0.3% ± 4.1%), but there was an increase after NO3 (6.5% ± 11.4%) (P = .049; d = 0.79). No differences were observed between the 30-s isokinetic trials. Acute NO3- supplementation can enhance maximal muscle power in trained athletes. These findings may particularly benefit power-sport athletes who perform brief explosive actions.

Aerobic Exercise Training Increases Muscle Water Content in Obese Middle-Age Men.

The objective of this study is to determine whether muscle water content (H2Omuscle) expands with training in deconditioned middle-age men and the effects of this expansion in other muscle metabolites. Eighteen obese (BMI = 33 ± 3 kg⁻¹·m⁻²) untrained (V˙O2peak = 29 ± 7 mL⁻¹·kg⁻¹·min⁻¹) metabolic syndrome men completed a 4-month aerobic cycling training program. Vastus lateralis muscle biopsies were collected before and 72 h after the completion of the last training bout. Water content, total protein, glycogen concentration, and citrate synthase activity were measured in biopsy tissue. Body composition was assessed using dual-energy X-ray absorptiometry, and cardiometabolic fitness was measured during an incremental cycling test. Body weight and fat mass were reduced -1.9% and -5.4%, respectively (P < 0.05), whereas leg fat free mass increased with training (1.8%, P = 0.023). Cardiorespiratory fitness (i.e., V˙O2peak), exercise maximal fat oxidation (i.e., FOmax), and maximal cycling power (i.e., Wmax) improved with training (11%, 33%, and 10%, respectively; P < 0.05). After 4 months of training, H2Omuscle increased from 783 ± 18 to 799 ± 24 g·kg⁻¹ wet weight (ww) (2%, P = 0.011), whereas muscle protein concentration decreased 11% (145 ± 15 to 129 ± 13 g·kg⁻¹ ww, P = 0.007). Citrate synthase activity (proxy for mitochondrial density) increased by 31% (17 ± 5 to 22 ± 5 mmol·min⁻¹·kg⁻¹ ww, P = 0.024). Muscle glycogen concentration increased by 14% (22 ± 7 to 25 ± 7 g·kg⁻¹ ww) although without reaching statistical significance when expressed as per kilogram of wet weight (P = 0.15). Our findings suggest that aerobic cycling training increases quadriceps muscle water although reduces muscle protein concentration in obese metabolic syndrome men. Reduced protein concentration coexists with increased leg lean mass suggestive of a water dilution effect that however does not impair increased cycling leg power with training.

The Effect of Dietary Nitrate Supplementation on Maximal Cycling Power

Muscle shortening velocity and power increase in the presence of nitric oxide (NO). NO bioavailability increases after consuming foods rich in dietary nitrate. There is a very high concentration of nitrate in concentrated beetroot juice. PURPOSE: The purpose of this study was to determine if beetroot juice can increase maximal cycling power compared to a nitrate-depleted beetroot juice placebo. METHODS: In this double-blind, crossover study, acute changes in maximal cycling power were determined after beetroot juice supplementation or consumption of a placebo. During each of four visits, seven trained athletes (n=5 cyclists, 2 alpine skiers) performed four bouts of maximal cycling (∼3s) using an inertial load cycle ergometer immediately before, then 2.5h after consuming a bolus (140ml) of either nitrate-rich (∼11.2mmol) beetroot juice or a nitrate-depleted placebo. A 2x2 Repeated Measures ANOVA was used to assess main effects of time (pre- vs. post-drink) and treatment (beetroot juice vs. placebo), and the interaction between time and treatment (α=0.05). RESULTS: There was a main effect for time (p=0.002), but not for treatment (p=0.14). There was a trend toward an interaction between time and treatment (p=0.11). Specifically, there was a greater increase in maximal power from pre- to post-beetroot juice supplementation (1071±321W vs 1134±339W) compared to the increase observed in the placebo trial (1117±315W vs. 1154±322W). CONCLUSIONS: The main effect for time was a somewhat unexpected finding. All pre-drink trials happened early in the morning (before 8:00 am), and the post-drink trials happened mid-morning (∼9:00-10:45 am). Therefore, our results may have been confounded by the circadian rhythm in core temperature and muscle power. Nevertheless, there was still a trend toward increased maximal power after beetroot juice supplementation in trained athletes compared to the observed increase after consuming the placebo. These findings warrant more research to determine if indeed dietary nitrate can increase maximal cycling power.

Noncircular Chainrings Do Not Improve Maximum Cycling Power and Joint-Specific Power during Maximal Cycling

Net cycling power is mainly produced during leg extension and flexion actions with minimal power produced during the transition between extension and flexion. A possible strategy to maximize cycling power is to increase the time spent in extension and flexion, while decreasing the time spent in transition. Noncircular (NC) chainrings can be oriented to prolong the powerful leg extension phase by varying crank angular velocity (ω) within the pedal cycle. However, the degree to which instantaneous crank ω influence muscle and joint actions depends on the degrees of freedom (DOF) in the leg/crank/pedal system. Previous investigations on cycling power using NC chainrings have produced mixed findings. These mixed findings may be due to cyclists exploiting redundant DOF in the leg/crank/pedal system to manipulate joint ω independent of crank ω. PURPOSE: To evaluate the effects of NC chainrings on joint-specific kinematics and power production during maximal cycling. METHODS: Ten healthy trained cyclists (age=34±8yr, mass=72±9kg, height=1.8 ±0.1m) performed maximal cycling trials of 3 s at randomly assigned pedaling rates (60, 90, and 120 rpm), and chainring eccentricities (ratio of major-to-minor axis) of 1.0 (Cir), 1.13 (Rotor), and 1.24 (Osym), respectively. Participants were visually blinded to chainrings. Joint-specific powers were averaged over complete pedal revolutions and extension-flexion phases. Joint-specific kinematics were analyzed for the portion of the pedal cycle where NC chainrings imposed 80% of their eccentricities (ECC80) on crank ω. RESULTS: Joint-specific powers were unaffected by chainring eccentricity. Ankle extension ω was significantly reduced (-13±12% and -37±13% at 90 and 120 rpm, respectively; all p<0.05) with the Osym chainring, whereas knee and hip extension ω were unaffected. Crank ω, ankle, knee, and hip extension ω within ECC80 increased with increasing pedaling rates (all p<0.01). CONCLUSION: NC chainrings did not improve maximum cycling power or alter joint-specific power during maximal cycling. Knee and hip ω remained unaffected with only ankle ω affected by chainring eccentricity. These results suggest that the effects of the NC chainrings on crank ω were eliminated by the cyclists’ ankling action and thus did not alter the major power producing actions of the hip and knee.