Relative Power Output Research Articles

Effects of Body Weight vs. Lean Body Mass on Wingate Anaerobic Test Performance in Endurance Athletes.

The aim of this study was to determine the influence of body weight or lean body mass-based load on Wingate Anaerobic Test performance in male and female endurance trained individuals. Thirty-one participants (22 male cyclists and triathletes and 9 female triathletes) completed two randomized Wingate Anaerobic Test (body weight and lean body mass loads) in stationary start. There were no significant differences in power outputs variables between loads in any group. However, when comparing specific groups within the sample (e. g. cyclists vs cyclists) medium to large effect sizes were observed for Relative Mean Power Output (ES=0.53), Relative Lowest Power (ES=0.99) and Relative Power Muscle Mass (ES=0.54). Regarding gender differences, male cyclists and triathletes displayed higher relative and absolute power outputs (p<0.001) compared to female triathletes regardless of the protocol used. FI was lower in female triathletes compared to male triathletes and cyclists in body weight (p<0.001) and lean body mass (p<0.01) protocols. Body composition and anthropometric characteristics were similar in male cyclists and triathletes, but there were differences between genders. These results suggest that using either body weight-based or lean body mass-based load can be used interchangeably. However, there may be some practically relevant differences when evaluating this on an individual level.

Exercising control over signs and symptoms of stress and depression

300 million people worldwide suffer from depression. A poorly understood stress‐related pathophysiology is compounded by frequent treatment‐resistance.Undertaking regular exercise has consistently shown to prevent, protect and increase resilience against the development of aberrant stress‐related responses seen in depression, whereas sedentary behaviour tends to heighten symptoms. Despite the promise shown by exercise its clinical use is undermined by poor understanding of how beneficial effects are produced.Stress exposure can dysregulate important physiological pathways such as the hypothalamic‐pituitary‐adrenal (HPA) axis and the sympathetic nervous system. Disruption of tryptophan metabolism, including increased metabolism along the kynurenine pathway, is a neurobiological hallmark of depressed patients. Recent studies have shown that the beneficial impact of exercise for mood and cognition may be linked to reduced kynurenine production.Aimto examine the benefits of a 12‐week exercise programme in healthy but sedentary adults across mood, stress, anxiety and depression were mediated by the regulation of tryptophan metabolism in a dose dependent manner.32 healthy sedentary participants (16 female) were analysed. To establish a baseline profile each participant undertook a battery of psychometric assessments, cognitive assessments and a cycle ergometer‐based incremental fitness assessment. Measures of oxygen uptake and capillary blood lactate levels were taken at the end of each stage during the fitness assessment.After the baseline assessment, participants were randomised into one of four groups (high, moderate, low dose exercise, or sedentary control group). Exercise was administered over 3 sessions/week based on individual fitness and group. Monthly fitness and psychometric assessments were performed throughout to monitor change across the 12‐week exercise programme. Analyses performed using SPSS.As expect, participants showed a positive increase in fitness and performance with an increase in maximal oxygen uptake (F(1,28)=14.62, p=.001, ηp2=.343) after 12‐weeks exercise training, accompanied by an increased relative peak power output (rPPO) (F(1,28)=16.93, p=.000, ηp2=.377) and an increased time to exhaustion (T2Ex) (F(1,28)=31.07, p=.000, ηp2=.526). Post hoc paired T‐tests revealed that the most pronounced effects on rPPO and T2Ex occurred in the moderate or high intensity groups There was a reduction in scores on the Beck Depression Inventory (BDI) (F(1,28)=6.50, p=.017, ηp2=.189) and the Perceived Stress Scale (PSS) (F(1,28)=4.09, p=.053, ηp2=.127) scores after 12 weeks of exercise.In sum, these results confirm that exercise training beneficially influences measures of stress and depression. Further work is required to understand the role of exercise‐induced alterations in tryptophan metabolism in mediating these effects.Support or Funding InformationAPC Microbiome Ireland is a research center funded by Science Foundation Ireland (SFI), through the Irish Government’s National Development Plan (grant no. 12/RC/2273). GC, JFC and TD are supported by the Irish Health Research Board (Grant number ILP‐POR‐2017‐013). CEG is supported by European Foundation for the Advancement in Neurosciences, Geneva, Switzerland.

Translating Ramp V˙O2 into Constant Power Output: A Novel Strategy that Minds the Gap.

This study aimed to model the dissociation in the V˙O2/power output (PO) relationship between ramp incremental (RI) and constant work rate (CWR) exercise and to develop a novel strategy that resolves this gap and enables an accurate translation of the RI V˙O2 response into a constant PO. Nine young men completed two RI tests (30 and 15 W·min) and CWR tests at seven intensities across exercise intensity domains. The V˙O2/PO relationship for RI and CWR exercise was modeled, and the dissociation was compared in terms of PO. The accuracy of three translation strategies was tested in the moderate-intensity (i.e., zone 1) and heavy-intensity (i.e., zone 2) domain. Strategy 1 comprised a simple mean response time correction, whereas strategies 2 and 3 accounted for the loss of mechanical efficiency in zone 2 by applying an extra correction that was based on, respectively, the difference between s2 - CWR and s2 - ramp and the ratio s2/s1. For all intensities, differences in PO were found between CWR and RI exercise (P < 0.001). Overall, these differences were smaller for the 15-W·min compared with the 30-W·min protocol (P = 0.012). Strategy 1 was accurate for PO selection in zone 1 (bias = 0.4 ± 7.3 W), but not in zone 2 (bias = 17.1 ± 15.9 W). Only strategy 2 was found to be accurate for both intensity zones (bias = 2.2 ± 14.2 W) (P = 0.107). This study confirmed that a simple mean response time correction works for PO selection in the moderate-intensity but not in the heavy-intensity domain. A novel strategy was tested and validated to accurately prescribe a constant PO based on the RI V˙O2 response in a population of young healthy men.

Case Study: Resumption of Eumenorrhea in Parallel With High Training Load After 4 Years of Menstrual Dysfunction: A 5-Year Follow-Up of an Elite Female Cyclist.

The female athlete triad is a condition where low energy availability is typically observed together with menstrual dysfunction and/or low bone mineral density. How this condition affects maximal work capacity in endurance athletes is not clear, and the recovery time course of menses with increased energy availability with concomitant high training load is unknown. This case study of an amenorrheic elite road cyclist reports resumption of normal menstrual function after weight gain during a 5-year period (2014-2019), while engaged in high training load and competition. The athlete (V˙O2max 3.54L/min, 64ml·min-1·kg-1, aerobic peak power output 300W, 5.4W/kg) reported amenorrhea (2013-2015) and oligomenorrhea (2015-2018). Training load increased from 2014 to 2019 (584-818hr/year and 26,707-41,945 training stress score/year). Regular menses (every 23-35 days) resumed in June 2018, ∼5-6 months after a weight gain episode. During the period of menstrual dysfunction, body mass was 51.3 ± 2.25kg (mean ± 95% confidence limit) and fat percentage was 19% (dual-energy X-ray absorptiometry, 2016), and after weight gain, body mass was 56.8 ± 2.63kg and fat percentage was 25% (dual-energy X-ray absorptiometry, 2019). Crank-based power meter data showed absolute mean maximal power (in watts) improvement over the 5s to 4hr range through the 2014-2019 period, while relative mean maximal power (in watts per kilogram) likely peaked in the 2015-2016 season for 5min, 20min, and 30min, but remained mostly unchanged across seasons. Results suggest that (a)the best relative power output associated with aerobic capacity (5min to 1hr) can be achieved during menstrual dysfunction, (b)high performance achieved despite an increase in body mass, and (c)resumption of menses is achievable while maintaining high training loads when coupled with high energy availability.

CORRELATION ANALYSIS OF OLYMPIC-STYLE WEIGHTLIFTING EXERCISES AND VERTICAL JUMPS

ABSTRACTPURPOSE Many types of vertical jumps (VJ) are commonly used to assess the development of the level of explosive strength of lower limbs achieved after a training period. This study is focused on comparing various parameters of different types of VJ with 1 RM in Olympic-style weightlifting, squat and deadlift with an Olympic bar.METHODS Twelve elite weightlifters (men=8; women=4; age 26±4 years, height = 173±8 cm; weight 93±23 kg; weight category from 64 kg to +109 kg) were tested for 1 RM in the following exercises: snatch, clean and jerk, deadlift, squat and variations of VJ on dynamometric plates (Kistler Force Plate). The variations of VJ were: squat jump with the arm swing (SJA) and non-arm swing (SJ), countermovement jump with the arm swing (CMJA) and non-arm swing (CMJ). The parameters compared for each type of VJ were: jump height (m), relative force (% of body weight), relative power (W/kg of body weight) and average power (W). For statistical analysis, the parametric Pearsons correlation coefficient with α=0.05 was used. RESULTS The results show a significant correlation between 1 RM in exercises with an Olympic bar (snatch, clean and jerk, back squat and deadlift) and the CMJ, CMJA, SJ and SJA only in the average power output (W) parameter (p&lt;0.05). The significant correlation coefficients in the average power output (W) were for the CMJA and the snatch r=0.96 r2= 0.92, clean and jerk r=0.96 r2= 0.92, back squat r=0.97 r2= 0.94 and deadlift r=0.93 r2= 0.86; CMJ with hands on the hips and the snatch r=0.93 r2= 0.86, clean and jerk r= 0.93 r2= 0.86, back squat r= 0.95 r2= 0.90 and deadlift r= 0.94 r2= 0.88; for the SJA and the snatch r=0.8 r2= 0.64, clean and jerk r=0.81 r2= 0.65, back squat r=0.82 r2= 0.67 and deadlift r=0.78 r2= 0.60; for the SJ with hands on the hips and the snatch r= 0.76 r2= 0.57, clean and jerk r= 0.75 r2= 0.56, back squat r= 0.77 r2= 0.59 and deadlift r= 0.71 r2= 0.50. Significant correlation coefficients were not found for 1 RM in the snatch, clean and jerk, back squat and deadlift and the CMJ or SJ with and without arm swing in any of the following parameters: jump height (m), relative force (% of body weight), relative power output (W/kg of body weight).CONCLUSION The main finding is that the jump height (m) of the CMJ or SJ with or without arm swing did not correlate significantly with 1 RM in the snatch, clean and jerk, back squat and deadlift. Therefore, jump height measurement can be used as a motivation tool but not to predict maximum strength in Olympic bar exercises, or vice versa. We recommend using the average power output (W) parameter in the CMJ with using arms as a predictor of current performance level in exercises with an Olympic bar for men and women.Key words: snatch, clean and jerk, squat, deadlift, countermovement jump, squat jump

The relative peak power output of amateur mountain bikers is inversely correlated with body fat but not with fat-free mass

Aims: To evaluate whether body mass (BM) and body composition may influence mountain bike cycling performance. Methods: Forty male amateur mountain bikers attended the laboratory on two non-consecutive days. At the first visit, anthropometric measures (height, BM, body fat [BF], fat-free mass [FFM] and body mass index [BMI]) and familiarization to incremental cycling test were performed. On the second visit, cyclists performed again the incremental cycling test to measure peak power output (PPO), peak power output relative to BM (PPO-BM), and time to exhaustion (TE), which were posteriorly correlated with BM and anthropometric measures. Results: A low and moderate significant correlation were observed between TE and BM (p<0.01; r=0.40) and FFM (p<0.01; r=0.56). Moderate significant correlation was found between PPO and BM (p<0.01; r=0.45), BMI (p=0.03; r=0.35) and strong with FFM (p<0.01; r=0.59). Also, PPO-BM significantly correlated with BM (p=0.04; r=-0.31), BMI (p=0.02; r=-0.35) and BF (p<0.01; r=-0.55). No other significant correlations were observed. Conclusion: Considering PPO-BM as mainly performance variable, BM and BF can be a determining factor in mountain biking performance but FFM did not.

The effect of somatotype characters on selected physical performance parameters

Background and Study Aim: The physical structure is considered as one of the elements for sporting success. The aim of this study was to investigate the effects of somatotype characters on selected physical performance parameters. Material and Methods: This study was included 150 males (age: 22.10±2.46 years) participants who do not have habit of regular exercise. The somatotype characters of participants were determined and physical performance tests (30 m sprint, vertical jump, anaerobic power, aerobic capacity, and flexibility) were measured as an experimental design. Results: As a result of the research, 9 different somatotype subgroups were identified. In this study, the statistically significant was found between groups in terms of explosive force, aerobic and anaerobic power output (p&lt;0.05). We found no significant between groups in terms of flexibility (p=0.670), relative anaerobic peak (p=0.560) and mean power output (p=0.077). The results were obtained in favor of mesomorph-endomorph structure in terms of absolute peak and mean power, while mesomorph and ectomorph component contributed positively to explosive force and aerobic capacity scores.Conclusion: Our study highlighted the fact that the subgroups of somatotype have an effect on performance parameters. The body-performance relationship can be examined in detail with more participants representing each somatotype group.

Motor learning outcomes of handrim wheelchair propulsion during active spinal cord injury rehabilitation in comparison with experienced wheelchair users

Purpose To investigate changes in wheelchair propulsion technique and mechanical efficiency across first five weeks of active inpatient spinal cord injury rehabilitation and to compare the outcomes at discharge with experienced wheelchair users with spinal cord injury. Methods Eight individuals with recent spinal cord injury performed six weekly submaximal exercise tests. The first and last measurement additionally contained a wheelchair circuit and peak graded exercise test. Fifteen experienced individuals performed all above-mentioned tests on one occasion. Results Mechanical efficiency and propulsion technique did not change during the five weeks of inpatient rehabilitation. Peak power output during peak graded test and performance time on the wheelchair circuit improved between the first and the last week. No difference in propulsion technique, peak power output, and performance time was found between the persons with a recent injury and the experienced group. Mechanical efficiency was higher after the correction for the difference in relative power output in the experienced group. Conclusion The group with a recent injury did not improve mechanical efficiency and propulsion technique over the period of active rehabilitation, despite significant improvements on the wheelchair circuit and in work capacity. The only significant difference between the groups was found in mechanical efficiency. Implications for rehabilitation The lack of time-dependent changes in mechanical efficiency and propulsion technique in the group with a recent spinal cord injury, combined with the lack of differences in technique, work capacity and on the wheelchair circuit between the groups, suggest that important adaptations of motor learning may happen even earlier in rehabilitation and emphasize that the group in active rehabilitation was relatively skilled. Standardized observational analyses of handrim wheelchair propulsion abilities during early spinal cord injury rehabilitation provide detailed understanding of wheelchair technique, skill as well as wheelchair propulsion capacity. Measurement of external power output is critical to interpretation of gross efficiency, propulsion technique, and capacity. Wheelchair quality and body weight – next to wheelchair fitness and skill – require careful consideration both in early rehabilitation as well as in the chronic phase of spinal cord injury.

Mean Propulsive Velocity Is a Viable Method for Adjusting the Resistance-Training Load at Moderate Altitude.

We examined the viability of using mean propulsive velocity (MPV) to adjust the load in the countermovement jump (CMJ) at moderate altitude. Twenty-four volunteers were assigned to a 4-week power-oriented resistance training (RT) program in either normoxia (N, 690 m) or intermittent hypobaric hypoxia (IH, 2,320 m). The load was adjusted to maintain execution velocity of CMJ at 1m·s−1 of MPV. Relative peak power output (Prel), and percentage of velocity loss throughout the sets (VL) were determined for each session. The internal load was measured by the rating of perceived exertion (RPE). The absolute load lifted was higher in IH compared to N (75.6 ± 8.4 vs. 58.5 ± 12.3 kg P < 0.001). However, similar relative increases for both groups were found when comparing the final values (IH: 8.2%, P = 0.007; N: 9.8%, P = 0.03) with no changes in VL between groups (P = 0.36). Post-study Prel improved significantly only in IH (+7% W·kg−1, P = 0.002). Mean RPE was greater in IH vs. N (6.8 ± 1.5 vs. 5.6 ± 2, P < 0.001). The MPV seems to be a viable method for adjusting external load during RT at moderate altitude. However, given that RT at moderate altitude increases RPE, it is prudent to monitor internal load when using the MPV to best determine the actual physiological stress of the session.

The Associations of Vitamin D Status with Athletic Performance and Blood-borne Markers in Adolescent Athletes: A Cross-Sectional Study.

The purpose of this study was to examine the associations of vitamin D status with athletic performance and blood-borne markers in adolescent athletes. This cross-sectional study included forty-seven Taekwondo athletes, aged 15–18 years old. Athletic performance was assessed using maximal oxygen consumption (VO2max), Wingate anaerobic power test, vertical jump, agility T-test, lower limb muscle strength, and fatigue resistance. Blood samples were collected to assess serum 25-hydroxyvitamin D [25(OH)D], free-testosterone, cortisol, creatine kinase, and urea. One-way ANOVAs were applied using Bonferroni adjusted alpha levels, which was 0.02 (i.e., 0.05/3). Multiple linear regressions analyses as well as Pearson and partial correlation analyses were used to examine the relationship among 25(OH)D concentration, athletic performance, and blood-borne markers. The participants 25(OH)D concentration were ranged from 16 to 73.25 nmol/L, indicating that 74.5% of the adolescent athletes have vitamin D insufficiency or deficiency. The vitamin D status did not show any significant effects on the performance factors or blood-borne markers. Serum 25(OH)D concentration was positively correlated with mean power output (r = 0.359, p < 0.05) and relative mean power output (r = 0.325, p < 0.05) after adjusting for bone age, height, weight, training experience, lean body mass, and fat mass. However, 25(OH)D concentration was not associated with other performance-related factors and blood-borne markers. In addition, multiple linear regressions analyses revealed that serum 25(OH)D concentration were not significant predictors of athletic performance in adolescent athletes. In conclusion, vitamin D status is weakly correlated with anaerobic capacity; moreover, the underlying mechanisms of how vitamin D influence anaerobic performance is unclear in the present study. Nevertheless, the importance of vitamin D on health benefits should not be underestimated, especially during growth periods.

Modality-specific training adaptations - do they lead to a dampened acute inflammatory response to exercise?

While adaptations to a short-term training program can dampen the acute inflammatory response to exercise, less is known about the influence of chronic modality-specific adaptations to training. This study compares the acute inflammatory response to upper- and lower-body interval exercise in individuals chronically trained in these respective modalities. Ninety minutes of interval exercise matched for relative power output on an arm-crank (ARM) and cycle ergometer (LEG) was performed by 8 trained paddlers and 8 trained cyclists. Blood samples were taken before and after exercise. Interleukin-6 (IL-6) concentrations were analysed in plasma, while the expression of intracellular heat shock protein 72 (iHsp72) was assessed in monocytes. IL-6 was increased following both modalities (fold change - ARM: 7.23 ± 3.56, p < 0.001; LEG: 9.03 ± 4.82, p < 0.001), in both groups (cyclists, p < 0.001; paddlers, p < 0.001), but the increase was smaller in ARM compared with LEG (time × modality, p < 0.001). ARM induced a smaller iHsp72 response compared with LEG (fold change - ARM: 1.07 ± 0.14, p = 0.102; LEG: 1.18 ± 0.14, p < 0.001; time × modality, p = 0.039). Following ARM, iHsp72 expression was increased in the cyclists only (fold change cyclists: 1.12 ± 0.11, p = 0.018; paddlers: 1.03 ± 0.17, p = 0.647), while iHsp72 expression following LEG was increased in both groups (fold change cyclists: 1.14 ± 0.15, p = 0.027; paddlers: 1.22 ± 0.13, p < 0.001). Taken together, the acute inflammatory response to lower-body interval exercise was larger compared with work-matched upper-body interval exercise. Moreover, adaptations to upper-body exercise training dampened the iHsp72 response to this modality. Therefore, exercise may be less effective in reducing chronic low-grade inflammation in individuals relying on their upper body, such as wheelchair users.

In-season in-field variable resistance training: effects on strength, power, and anthropometry of junior soccer players.

Soccer players' leg muscular strength and power have been shown to be significant due to their association with soccer-specific performance including jumps, sprints, tackles and kicks. The aim of this study, therefore, was to examine the effects of an in-season in-field variable resistance training (VRT) program on strength, power, and anthropometry of junior soccer players. A team of male soccer players were randomly assigned into Experimental (N.=10) and Control groups (N.=10). The Control group performed 8 weeks of soccer training alone. The Experimental group performed squat VRT using chains in addition to soccer training. Measures before and after training included squat strength, countermovement jump, and anthropometric estimation of thigh muscle cross sectional area (CSA). The VRT induced large improvements in absolute (34.45%; P=0.001; Cohen's d=1.78) and relative strength to thigh muscle CSA (21.53%; P=0.002; Cohen's d=1.04). Similarly, there were large (18.07%, P=0.007; Cohen's d=1.5) increases in jump height and medium gains in absolute peak power output (16.13%; P=0.009; Cohen's d=0.34) and relative peak power output to thigh muscle CSA (9.6%; P=0.002; Cohen's d=0.31). Further, there was a medium increase (5.9%, P=0.03; Cohen's d=0.36) in thigh muscle CSA. No significant changes were observed in the Control group. In-season in-field biweekly squat VRT enhanced strength and power measures in junior soccer players.

Performance enhancement of Wells turbine: Combined radiused edge blade tip, static extended trailing edge, and variable thickness modifications

The Wells turbine is used in conjunction with an oscillating water column to harvest wave energy. It is a self-rectifying axial flow reaction turbine which consists of symmetrical blades aligned normal to the incoming flow. A narrow operating range due to flow separation restricts the power extracting capability of the turbine at a higher flow rate. To improve its performance, a turbine blade with combined design modifications such as radiused edge blade (REB) tip, static extended trailing edge (SETE) and variable thickness blade (VTB) was investigated through CFD analysis. Three-dimensional time independent Reynolds-averaged Navier-Stokes equations were solved in a commercial solver to obtain the turbine performance, which was given by non-dimensional torque, pressure drop and efficiency. The combined REB tip, SETE and VTB modifications enhanced relative average turbine power output by 97% and the relative operating range by 22%. However, the average efficiency is decreased by 7.7%, because of the increased pressure drop.

Log-Transformed Electromyography Amplitude-Power Output Relationship: Single-Leg Knee-Extensor Versus Single-Leg Cycle Ergometry.

Noble, EB, Pilarski, JM, Vora, HK, Zuniga, JM, and Malek, MH. Log-transformed electromyography amplitude-power output relationship: single-leg knee-extensor versus single-leg cycle ergometry. J Strength Cond Res 33(5): 1311-1319, 2019-Comparing and contrasting motor unit recruitment and activation for the same muscles for multiple versus single-joint exercise may provide a better understanding of neuromuscular fatigue. The purpose of this study, therefore, is to compare the slope and y-intercept terms for the 3 superficial quadriceps femoris (QF) (vastus lateralis, rectus femoris, and vastus medialis) muscles derived from the log-transformed electromyography (EMG) amplitude-power output relationship between the single-leg knee-extensor ergometry (KE) and the single-leg cycle ergometry (CE). Ten healthy college-aged men who engaged in regular physical activity visited the laboratory on 2 occasions separated by 7 days to perform either single-leg CE or single-leg KE in a randomized order. For each visit, subjects performed incremental exercise until voluntary fatigue. Electromyography electrodes were placed on the superficial QF muscles. The slope and y-intercept terms, for each muscle, for the EMG amplitude versus power output relationship was examined using the log-transformed model for each subject's data. The results indicated no significant (p > 0.05) mean differences for either slope or y-intercept terms between exercise modes and across muscles. In addition, separate repeated-measures analyses of variance (ANOVAs) were used to determine mean differences for the slope and y-intercept values between the 3 muscles. In addition, separate 2 (mode: CE or KE) × intensity (intensity: 30, 60, and 90% of maximal workload) repeated-measures ANOVAs were conducted for each muscle. There was a significant (p < 0.05) mode × exercise intensity interaction for each muscle. Follow-up testing indicated that in most cases, the normalized EMG amplitude was significantly higher for single-leg KE than single-leg CE. These results indicated that incremental single-leg KE activates the superficial QF muscles significantly greater than single-leg CE.

A Loss Separation Method of a High-Speed Magnetic Levitated PMSM Based on Drag System Experiment Without Torque Meter

Varieties of loss should be optimized to be as little as possible for the stability of the permanent magnet in a high-speed magnetic levitated permanent magnet synchronous motor (HSMLPMSM) rotor and ensure the high efficiency and low temperature of the motor. First, this paper analyzes loss distribution in a motor, whose power and rated speed are 100 kW and 32 000 r/min, by a calculation method. Then, separation of losses of the HSMLPMSM is implemented based on a drag system without torque meter accounting for its particularity of high-power and high-speed level. In all kinds of losses, core loss and coil loss can be separated by a traditional calculation method with related parameters being tested. Besides, windage loss and magnetic bearing loss can be obtained by a deceleration test. Resulting from power balance equations deduced by the relationship of the drag system's power input and output, eddy current loss of the rotor can be separated, compared to its finite-element analysis results and analytical results. In the end, with thermal-electromagnetic coupled analysis, loss separation results are validated via temperature rise experiment indirectly.

Sex Differences in Performance and Pacing Strategies During Sprint Skiing.

Purpose: This study aimed to compare performance and pacing strategies between elite male and female cross-country skiers during a sprint competition on snow using the skating technique.Methods: Twenty male and 14 female skiers completed an individual time-trial prolog (TT) and three head-to-head races (quarter, semi, and final) on the same 1,572-m course, which was divided into flat, uphill and downhill sections. Section-specific speeds, choice of sub-technique (i.e., gear), cycle characteristics, heart rate and post-race blood lactate concentration were monitored. Power output was estimated for the different sections during the TT, while metabolic demand was estimated for two uphill camera sections and the final 50-m flat camera section.Results: Average speed during the four races was ∼12.5% faster for males than females (P < 0.001), while speeds on the flat, uphill and downhill sections were ∼11, 18, and 9% faster for the males than females (all P < 0.001 for terrain, sex, and interaction). Differences in uphill TT speed between the sexes were associated with different sub-technique preferences, with males using a higher gear more frequently than females (P < 0.05). The estimated metabolic demand relative to maximal oxygen uptake (O2max) was similar for both sexes during the two uphill camera sections (∼129% of O2max) and for the final 50-m flat section (∼153% of O2max). Relative power output during the TT was 18% higher for males compared to females (P < 0.001) and was highly variable along the course for both sexes (coefficient of variation [CV] between sections 4–9 was 53%), while the same variation in heart rate was low (CV was ∼3%). The head-to-head races were ∼2.4% faster than the TT for both sexes and most race winners (61%) were positioned first already after 30 m of the race. No sex differences were observed during any of the races for heart rate or blood lactate concentration.Conclusion: The average sex difference in sprint skiing performance was ∼12.5%, with varying differences for terrain-specific speeds. Moreover, females skied relatively slower uphill (at a lower gear) and thereby elicited more variation in their speed profiles compared to the males.

Predictors of Linear and Multidirectional Acceleration in Elite Soccer Players.

Jonathan, N, Russell, M, Shearer, D, Cook, CJ, and Kilduff, LP. Predictors of linear and multidirectional acceleration in elite soccer players. J Strength Cond Res 33(2): 514-522, 2019-Linear and multidirectional acceleration underpins success in professional soccer match play. However, the physical qualities that determine these performance indicators are poorly understood in elite players. English Premier League players (n = 26) performed isometric midthigh pulls (IMTPs), bilateral and unilateral drop jumps (from 40 and 20 cm, respectively), bilateral and unilateral countermovement jumps (CMJs), and assessments of linear (5, 10, and 20 m) and multidirectional (left and right preplanned and reactive) acceleration. Regression analyses highlighted that 21% of variance in 5-m sprint time (1.02 ± 0.07 seconds) was explained by relative peak power output (PPO) in bilateral CMJ (54.5 ± 5.3 W·kg). A 5.4 W·kg increase in CMJ predicted a 0.03-second decrease in 5-m sprint time (P = 0.02). For 10-m sprint time (1.72 ± 0.09 seconds), 44% of variance was explained by isometric relative peak force ([PF]; 30.4 ± 4.9 N·kg) and bilateral relative CMJ PPO (54.5 ± 5.3 W·kg). A 5.4 W·kg increase in CMJ predicted reduced 10-m sprint times by 0.04 seconds (P = 0.01). For 20-m sprint time (2.94 ± 0.11 seconds), 55% of the total variance was explained by isometric relative PF (30.4 ± 4.9 N·kg) and relative CMJ PPO (54.5 ± 5.3 W·kg). Increases of 5.4 W·kg in bilateral CMJ predicted an improvement of 20-m sprint time by 0.06 seconds (P = 0.002). Contributions were insignificant (P > 0.05) for preplanned and reactive multidirectional acceleration. Relativized indices, especially those related to force production during CMJ and IMTP tests, likely underpin linear but not multidirectional acceleration performance in professional soccer players. When linear acceleration is a training focus, practitioners should seek to monitor CMJ and IMTP test performance.

Post-intense exercise sleep concerns in weightlifters: A pilot study

BackgroundWeightlifting is a power and dynamic strength game. Performance of weightlifters during competition depends on absolute and relative power output achieved by them. To enhance power and strength in weightlifters, training programmes have frequent high-intensity exercise sessions. On an informal interaction with the sportspersons, they often complain of problems after intense training. There was a felt need to analyse the problems they perceive after intense training. MethodA feedback form was developed after brainstorming with coaches and sports medicine physicians of a sports institute. Thirty-six male weightlifters aged 19.78 ± 4.71 yrs (mean ± standard deviation) of an institute participated after obtaining informed consent. The feedback form was collected and analysed. ResultAfter an intense exercise, participants reported complaints such as increased fatigue (n = 27), sleep problems (n = 26), restlessness (n = 18) and decreased appetite (n = 12). Of the sleep problems, 69.4% (n = 25 out of 36) noticed worsening of sleep, 50% (n = 18) noticed sleep was light after intense training, 58.3% (n = 21) felt difficulty in falling asleep, 47.2% (n = 7) complained of frequent waking up during sleep at night and 77.8% (n = 28) felt sleepy after waking up. ConclusionIntense training encounters certain problems such as fatigue, sleep disturbances, restlessness and decreased appetite.

Is the Functional Threshold Power a Valid Surrogate of the Lactate Threshold?

To analyze the relationship between functional threshold power (FTP) and the lactate threshold (LT). A total of 20 male cyclists performed an incremental test in which LT was determined. At least 48h later, they performed a 20-min time trial, and 95% of the mean power output was defined as FTP. Participants were divided into recreational (peak power output < 4.5W·kg-1; n = 11) or trained cyclists (peak power output > 4.5W·kg-1; n = 9) according to their fitness status. The FTP (240 [35]W) was overall not significantly different (effect size = 0.20; limits of agreement = -2.4% [11.5%]) from the LT (246 [24]W), and both markers were strongly correlated (r = .95; P < .0001). Accounting for the participants' fitness status, no significant differences were found between FTP and LT (effect size = 0.22; limits of agreement =2.1% [7.8%]) in trained cyclists, but FTP was significantly lower than the LT (P = .0004, effect size = 0.81; limits of agreement =-6.5% [8.3%]) in recreational cyclists. A significant relationship was found between relative peak power output and the bias between FTP and the LT markers (r = .77; P < .0001). FTP is a valid field test-based marker for the assessment of endurance fitness. However, caution should be taken when using FTP interchangeably with LT, as the bias between markers seems to depend on the athlete's fitness status. Whereas FTP provides a good estimate of LT in trained cyclists, in recreational cyclists, it may underestimate LT.

The Respiratory Compensation Point and the Deoxygenation Break Point Are Valid Surrogates for Critical Power and Maximum Lactate Steady State.

The Respiratory Compensation Point and the Deoxygenation Break Point Are Valid Surrogates for Critical Power and Maximum Lactate Steady State.