scholarly journals Statin myalgia is not associated with reduced muscle strength, mass or protein turnover in older male volunteers, but is allied with a slowing of time to peak power output, insulin resistance and differential muscle mRNA expression

2015 ◽  
Vol 593 (5) ◽  
pp. 1239-1257 ◽  
Author(s):  
Joanne E. Mallinson ◽  
Kanagaraj Marimuthu ◽  
Andrew Murton ◽  
Anna Selby ◽  
Kenneth Smith ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Muscle Strength ◽  
Mrna Expression ◽  
Power Output ◽  
Protein Turnover ◽  
Peak Power ◽  
Peak Power Output ◽  
Time To Peak ◽  
Male Volunteers

scholarly journals Graded reductions in preexercise muscle glycogen impair exercise capacity but do not augment skeletal muscle cell signaling: implications for CHO periodization

2019 ◽  
Vol 126 (6) ◽  
pp. 1587-1597 ◽  
Author(s):  
Mark A. Hearris ◽  
Kelly M. Hammond ◽  
Robert A. Seaborne ◽  
Ben Stocks ◽  
Sam O. Shepherd ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Signaling ◽  
Mrna Expression ◽  
Exercise Capacity ◽  
Muscle Cell ◽  
Muscle Glycogen ◽  
Power Output ◽  
Peak Power ◽  
Skeletal Muscle Cell ◽  
Peak Power Output

We examined the effects of graded muscle glycogen on exercise capacity and modulation of skeletal muscle signaling pathways associated with the regulation of mitochondrial biogenesis. In a repeated-measures design, eight men completed a sleep-low, train-low model comprising an evening glycogen-depleting cycling protocol followed by an exhaustive exercise capacity test [8 × 3 min at 80% peak power output (PPO), followed by 1-min efforts at 80% PPO until exhaustion] the subsequent morning. After glycogen-depleting exercise, subjects ingested a total of 0 g/kg (L-CHO), 3.6 g/kg (M-CHO), or 7.6 g/kg (H-CHO) of carbohydrate (CHO) during a 6-h period before sleeping, such that exercise was commenced the next morning with graded ( P < 0.05) muscle glycogen concentrations (means ± SD: L-CHO: 88 ± 43, M-CHO: 185 ± 62, H-CHO: 278 ± 47 mmol/kg dry wt). Despite differences ( P < 0.05) in exercise capacity at 80% PPO between trials (L-CHO: 18 ± 7, M-CHO: 36 ± 3, H-CHO: 44 ± 9 min), exercise induced comparable AMPKThr172 phosphorylation (~4-fold) and PGC-1α mRNA expression (~5-fold) after exercise and 3 h after exercise, respectively. In contrast, neither exercise nor CHO availability affected the phosphorylation of p38MAPKThr180/Tyr182 or CaMKIIThr268 or mRNA expression of p53, Tfam, CPT-1, CD36, or PDK4. Data demonstrate that when exercise is commenced with muscle glycogen < 300 mmol/kg dry wt, further graded reductions of 100 mmol/kg dry weight impair exercise capacity but do not augment skeletal muscle cell signaling. NEW & NOTEWORTHY We provide novel data demonstrating that when exercise is commenced with muscle glycogen below 300 mmol/kg dry wt (as achieved with the sleep-low, train-low model) further graded reductions in preexercise muscle glycogen of 100 mmol/kg dry wt reduce exercise capacity at 80% peak power output by 20–50% but do not augment skeletal muscle cell signaling.

Abstract P134: Preliminary Data: Dietary Nitrate Supplementation Does Not Extend Dry Static Apnea Or Wingate Performance

Circulation ◽  
2021 ◽  
Vol 143 (Suppl_1) ◽  
Author(s):  
Colin Carriker ◽  
Phillip Armentrout ◽  
Sarah Levine ◽  
James Smoliga
Keyword(s):  
Power Output ◽  
Preliminary Data ◽  
Repeated Measures ◽  
Peak Power ◽  
Hold Time ◽  
Wingate Test ◽  
Peak Power Output ◽  
Breath Hold ◽  
Dietary Nitrate ◽  
Nitrate Supplementation

Introduction: Previous studies have examined dietary nitrate supplementation and its effects on dry static apnea, and peak power. Dietary nitrate supplementation has been found to increase maximal apnea and peak power output. The purpose of this study was to determine the effects of beetroot juice on dry static apnea and Wingate performance. Hypothesis: Dietary nitrate will improve maximal breath hold time and peak power output. Dietary nitrate will improve tolerance to CO2, thereby improving maximal breath hold time and anaerobic capacity. Methods: In a randomized, double-blind, counterbalanced study, five healthy males (20.4±0.89 years) visited the lab on 3 separate occasions each separated by one week. Visit 1 served as a Wingate and breath hold familiarization visit. Prior to visits 2 and 3 participants were instructed to drink a beverage either a placebo (negligible nitrate content, PL) or dietary nitrate rich beverage (12.4 mmol nitrate, NIT) during the 4 days leading up to their next visit. Visits 2 and 3 consisted of two submaximal breath holds (80% of maximal determined during visit 1), with 2 minutes of rest between and three minutes of rest preceding the final breath hold for maximal duration. Finally, participants completed a standardized 10-minute warmup on the cycle ergometer before completing a 30-second maximal effort Wingate test. Results: A linear mixed effects model was used to determine whether treatment (NIT vs. PL) was associated with differences in VCO2 or PetCO2. Time (0, 10, 20, 30 min post-breath hold) and Treatment both served as repeated measures. Models were developed using multiple repeated measures covariance matrix structures, and the model with the lowest AIC was chosen as the final model. The interaction between time and treatment was included in the original models, and was removed if it was not statistically significant. Time was a statistically significant factor for VCO2 and PetCO2 (p < 0.001). Treatment, and the Time x Treatment interaction was not significant for either variable. No differences between NIT and PL were observed during the Wingate test for either time to peak power (5.02±2.45 and 6.2±2.43 sec, respectively) or maximal power (9.73±1.01 and 9.72±1.03 watts/kg, respectively) and fatigue index (49.42±14.98 and 47.30±6.99 watts/sec, respectively). Conclusion: Preliminary data indicates that in a general population four days of dietary nitrate supplementation may not improve breath hold time, tolerance to carbon dioxide in the lungs, or Wingate performance.

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

Arm muscle sympathetic nerve activity during preparation for and initiation of leg-cycling exercise in humans

1994 ◽  
Vol 77 (3) ◽  
pp. 1403-1410 ◽  
Author(s):  
R. Callister ◽  
A. V. Ng ◽  
D. R. Seals
Keyword(s):  
Power Output ◽  
Peak Power ◽  
General Pattern ◽  
Peak Power Output ◽  
Movement Initiation ◽  
Nerve Activity ◽  
Cycling Exercise ◽  
Target Power ◽  
Leg Cycling ◽  
Exercise In Humans

We tested the hypothesis that sympathetic vasoconstrictor nerve activity to nonactive skeletal muscle (MSNA) decreases immediately before and remains suppressed during initiation of conventional large muscle upright dynamic exercise in humans. In 11 healthy young subjects, adequate recordings of MSNA from the radial nerve in the arm were obtained during upright seated rest (control) and throughout 1 min of leg-cycling exercise at one or more submaximal workloads (range 33–266 W; approximately 10–80% of peak power output). MSNA was analyzed during four consecutive time intervals; control, preparation for cycling (end of control to onset of pedal movement), initiation of cycling (onset of pedal movement to attainment of target power output), and the initial 60 s of cycling at target power output. MSNA decreased (P < 0.05) abruptly and markedly in all subjects [to 19 +/- 4% (SE) of control levels] during the preparation period before the 33-W load and remained suppressed throughout the period of initiation of cycling in 8 of 11 subjects; MSNA increased during the initiation period in three subjects in whom diastolic arterial pressure fell below control levels. This general pattern was observed at all loads. MSNA remained at or below control levels throughout the 1 min of cycling exercise at 33–166 W. MSNA increased above control levels during the latter portion of the 1 min of cycling only at loads > or = 60% of peak power output.(ABSTRACT TRUNCATED AT 250 WORDS)

Peak Power Output Test on a Rowing Ergometer

2015 ◽  
Vol 29 (10) ◽  
pp. 2919-2925 ◽  
Author(s):  
Boris Metikos ◽  
Pavle Mikulic ◽  
Nejc Sarabon ◽  
Goran Markovic
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Peak Power Output ◽  
Rowing Ergometer

A constant-load ergometer for measuring peak power output and fatigue

1988 ◽  
Vol 65 (5) ◽  
pp. 2343-2348 ◽  
Author(s):  
J. H. Williams ◽  
W. S. Barnes ◽  
J. F. Signorile
Keyword(s):  
Power Output ◽  
Peak Power ◽  
Intraclass Correlation ◽  
Average Power ◽  
Load Cycle ◽  
Constant Load ◽  
Load Cell ◽  
Peak Power Output ◽  
Maximal Power Output ◽  
Power Curves

A constant-load cycle ergometer was constructed that allows maximal power output to be measured for each one-half pedal revolution during brief, high-intensity exercise. To determine frictional force, an electronic load cell was attached to the resistance strap and the ergometer frame. Dead weights were attached to the strap's free end. Flywheel velocity was recorded by means of a magnetic switch and two magnets placed on the pedal sprocket. Pedaling resulted in magnetically activated switch closures, which produced two electronic pulses per pedal revolution. Pulses and load cell output were recorded (512 Hz), digitized, and stored on disk via microcomputer. Power output was later computed for each pair of adjacent pulses, representing average power per one-half pedal revolution. Power curves generated for each subject were analyzed for peak power output (the highest one-half pedal revolution average), time to peak power, power fatigue rate and index, average power, and total work. Thirty-eight males performed two 15-s tests separated by 15 min (n = 16) or 48 h (n = 22). Peak power output ranged from 846.0 to 1,289.1 W. Intraclass correlation analysis revealed high test-retest reliability for all parameters recorded on the same or different days (R = 0.91-0.97). No significant differences (P greater than 0.05) were noted between parameter means of the first and second tests. These results indicate that the ergometer described provides a means for conveniently and reliably assessing short-term power output and fatigue.

Reducing Anxiety and Anxiety Sensitivity With High-Intensity Interval Training in Adults With Asthma

2020 ◽  
Vol 17 (8) ◽  
pp. 835-839
Author(s):  
Carley O’Neill ◽  
Shilpa Dogra
Keyword(s):  
Anxiety Sensitivity ◽  
Power Output ◽  
High Intensity ◽  
Peak Power ◽  
Interval Training ◽  
Peak Power Output ◽  
Sensitivity Index ◽  
High Intensity Interval Training ◽  
High Intensity Interval ◽  
The Impact

Background: Low- and moderate-intensity exercise training has been shown to be effective for reducing general anxiety and anxiety sensitivity among adults with asthma. Exercise frequency and intensity have been shown to play an integral role in reducing anxiety sensitivity; however, less is known about the impact of high-intensity interval training (HIIT) on anxiety in adults with asthma. Methods: A 6-week HIIT intervention was conducted with adults with asthma. Participants completed HIIT (10% peak power output for 1 min, 90% peak power output for 1 min, repeated 10 times) 3 times per week on a cycle ergometer. Preintervention and postintervention assessments included the Anxiety Sensitivity Index-3 and the Body Sensations Questionnaire. Results: Total Anxiety Sensitivity Index-3 (PRE: 17.9 [11.8]; POST 12.4 [13], P = .002, Cohen d = 0.4, n = 20) and Body Sensations Questionnaire (PRE: 2.4 [1.0]; POST: 2.0 [0.8], P = .007, Cohen d = 0.3) improved from preintervention to postintervention. Conclusion: A 6-week HIIT intervention leads to improved anxiety among adults with asthma. Future research should determine the impact of HIIT among adults with asthma with clinical anxiety.

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