This study explored differences in running economy between well-conditioned young male and female (tested within the early follicular phase of their menstrual cycle) participants, matched for age and ...percent difference between predicted and actual maximum oxygen uptake (V̇o
). Twenty-five recreational runners (13 men and 12 women), aged 19-27 yr, performed graded treadmill exercise to assess V̇o
. Participants also performed three bouts of submaximal continuous treadmill running at 8, 10, and 12 km/h. Sex comparisons revealed lower maximal aerobic speed (MAS) and V̇o
in women relative to men (
< 0.05). However, the percent difference from predicted V̇o
was similar between men and women (men: 149.6 ± 18.7%, women: 150.8 ± 16.4%;
> 0.05). Absolute running economy (mL·kg
·km
) improved in transition between treadmill speeds, and this occurred similarly in both sexes. Despite this, women showed overall lower oxygen cost of running than men during treadmill locomotion at predetermined absolute and relative intensities (
< 0.05). Finally, in a small subset of participants (
= 6, 3 male and 3 female participants) with similar MAS (16 km/h), men still exhibited higher V̇o
and gross oxygen cost of running than women (difference of ~6%, statistics not computed). The present results indicate that, in men and women with similar percent of predicted V̇o
, running economy follows a sexually dimorphic pattern throughout a broad spectrum of treadmill speeds. Ultimately, from a motor performance perspective, our data strongly suggest that lower V̇o
values in female recreational runners are partially compensated by lower gross oxygen cost of locomotion during submaximal running.
Our data demonstrate that, compared with that seen in men with similar percent difference from predicted maximum oxygen uptake (V̇o
), scaled gross oxygen cost of running (in absolute and relative terms) is lower in women throughout a broad spectrum of treadmill speeds. Importantly, these findings were obtained after controlling for the effects of the menstrual cycle on running economy, and this is novel.
Estimations based on the available equations for predicting oxygen uptake (V̇o
) from treadmill speed of locomotion are not appropriate for individuals with Down syndrome (DS). We aimed at developing ...prediction models for peak absolute oxygen uptake (V̇o
) and peak heart rate (HR
) based on retrospective data from a healthy population with and without Down syndrome (DS). A cross-sectional analysis of V̇o
and HR
was conducted in 196 and 187 persons with and without DS, respectively, aged from 16 to 45 yr. Nonexercise data alone versus combined with HR
were used to develop equations predictive of absolute V̇o
. Prediction equations for HR
were also developed. Two additional samples of participants (30 with, 29 without DS) enabled model cross-validation. Relative V̇o
and HR
were lowest for persons with DS across all ages (∼40% and 20 beats·min
, respectively). For persons with DS, V̇o
predictions provided no differences compared with actual values. Predicted HR
was similar to actual values in both groups of participants. Large limits of agreement were obtained for V̇o
(DS: 735, non-DS: 558.2 mL·min
) and HR
(DS: 24.8, non-DS: 16.6 beats·min
). Persons with DS exhibit low levels of V̇o
and HR
in all age groups included in this study. It is possible to estimate absolute V̇o
in persons with DS using nonexercise variables. HR
can be accurately estimated in groups of people with and without DS. Yet, because of large limits of agreement, caution is advised if using these equations for individual estimations of V̇o
or HR
in either population.
Our data show that it is possible to estimate absolute peak oxygen uptake in persons with Down syndrome using nonexercise variables. Peak heart rate can also be accurately estimated in groups of people with and without Down syndrome. However, because of large limits of agreement, caution is advised if using these equations for individual estimations of peak oxygen uptake or peak heart rate in either population.
Intermittent fasting (IF) has been studied in athletes during Ramadan and in those willing to decrease adiposity while maintaining or increasing lean body mass. The purpose of this systematic review ...was to summarize the effects of IF on performance outcomes. We searched peer-reviewed articles in the following databases: PubMed, Web of Science and Sport Discus (up to December 2019). Studies were selected if they included samples of adults (≥18 years), had an experimental or observational design, investigated IF (Ramadan and time-restricted feeding (TRF)), and included performance outcomes. Meta-analytical procedures were conducted when feasible. Twenty-eight articles met the eligibility criteria. Findings indicated that maximum oxygen uptake is significantly enhanced with TRF protocols (SMD = 1.32,
0.001), but reduced with Ramadan intermittent fasting (Ramadan IF; SMD = -2.20,
< 0.001). Additional effects of IF may be observed in body composition (body mass and fat mass). Non-significant effects were observed for muscle strength and anaerobic capacity. While Ramadan IF may lead to impairments in aerobic capacity, TRF may be effective for improving it. As there are few studies per performance outcome, more research is needed to move the field forward.
Optimal nutrition is highly valuable for athletes aiming at maintaining or improving body composition and sports performance. When combined with structured exercise, time-restricted energy intake may ...represent an effective nonpharmacological approach to achieving these results.
The aim of this study was to investigate the effects of 4 weeks of time-restricted eating (TRE) vs 4 weeks of habitual diet on aerobic capacity, body composition, and metabolic health in 18- to 30-year-old men accustomed to endurance running.
This trial used a randomized-crossover study design. Participants completed graded exercise tests, body composition scans, and fasting blood samples before and after each intervention condition.
Sixteen male physical education students were recruited and enrolled in the study from the Faculty of Human Kinetics—University of Lisbon in September 2020, in Lisbon, Portugal. One participant was excluded after 1 week because of a lack of adherence to the study protocol. Therefore, 15 participants completed the study and were involved in the final analysis.
During the TRE condition, participants consumed two to three meals within an 8-hour eating window (between 1:00 and 9:00 pm). Only water, tea, and coffee (without caloric additives) were permitted to be consumed in the remaining 16 hours per 24-hour period. During the non-TRE condition, participants consumed their habitual diet without any timing restrictions. The order of the TRE intervention and the habitual diet condition was randomized and counterbalanced, and participants served as their own controls. The participants followed a structured training routine during each dietary condition.
Body composition variables, indices of running aerobic capacity, and markers of metabolic health were assessed.
One-way repeated-measures analysis of variance and covariance were performed to analyze differences between conditions and time with each intervention.
Neither condition elicited observed changes in total body mass, fat mass, or fat-free mass between time points. Moreover, no significant changes were observed for markers of metabolic health. Significant improvements were obtained with both conditions for the first ventilatory threshold, maximum oxygen uptake (VO2max), and velocity at VO2max (P < 0.05).
Four weeks of endurance running and TRE, compared with 4 weeks of endurance running and a habitual diet, in healthy trained 18- to 30-year-old male recreational runners did not result in observed differences in total body mass, fat mass, or fat-free mass. In addition, TRE did not offer any additional benefit for improving submaximal or peak exercise capacity in this population.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Muscle fatigue is a limiting factor of human performance. It is unclear whether sex-based differences in fatigability exist during dynamic exercise of varying velocities of contraction. We aimed at ...exploring sex differences in muscle fatigue elicited by maximal isokinetic muscle contractions performed at different angular velocities. Twenty-six healthy participants (13 men: 23.2 ± 1.5; 13 women: 21.9 ± 3.0 years) were tested for concentric knee-extension at slow, moderate and fast angular isokinetic velocity (60, 180 and 300º.s
, respectively), on non-consecutive days. The impact of sex on fatigue resistance and consecutive recovery for each isokinetic condition was explored by calculating the percent change in maximal voluntary isometric contraction (MVIC) and in rate of torque development (RTD), from pre- to post-isokinetic exercise (30 repetitions). The isokinetic fatigue index was also determined. No sex differences were obtained in response to isokinetic contractions completed at 60º.s
. After performing muscle contractions at 300º.s
, women had a significantly greater loss in MVIC than men (- 18.4 ± 5.5 vs. - 12.9 ± 3.8%; p = 0.009) and larger decreases in work output during isokinetic exercise (- 34.2 ± 8.9 vs - 27.5 ± 10.6%; p = 0.017). Recovery of initial MVIC strength was greater for women post-exercise at 180º.s
(15.6 ± 4.1% vs. 6.7 ± 9.5; p = 0.003). No differences were found between sexes in any condition for RTD from pre- to post-fatigue. These results suggest the presence of a sexually dimorphic fatigability in response to dynamic (isokinetic) contractions favouring men at higher absolute velocities of contraction.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Purpose
There is some evidence that muscular activation during exercise is enhanced by higher levels of blood flow restriction (BFR). However, the impact of different relative levels of BFR on the ...acute neuromuscular response to resistance exercise is not yet fully understood. We examined the acute effects of low-intensity knee extensions 20 % of 1-repetition maximum (1RM) with BFR on muscle activation, neuromuscular fatigue and torque in the rectus femoris (RF) and vastus medialis (VM) muscles.
Methods
Fourteen men (24.8 ± 5.4 years) exercised at 20 % 1RM combined with 40, 60 and 80 % BFR. Restrictive pressures were calculated based on direct blood-flow measurements taken at rest on each participant. Torque was determined during pre- and post-exercise maximal voluntary contractions. Surface electromyographic activity root mean square (RMS) was obtained during dynamic and sustained isometric contractions before and after exercise. The median frequency (MF) of the electromyographic power spectrum was computed for isometric contractions.
Results
Torque only decreased in the 80 % BFR condition (−5.2 %;
p
< 0.01). Except for the VM in the 40 % BFR, MF decreased in both muscles post-exercise in all conditions (
p
< 0.01). MF decrements were of greater magnitude post-exercise at higher levels of BFR. RMS increased within all sets in both muscles (
p
< 0.01) and attained higher values in the 80 % BFR condition; except for set 1 in the RF muscle (
p
< 0.01).
Conclusion
Muscular activation, as well as neuromuscular fatigue, varies as a function of relative BFR intensity. Therefore, the individual determination of vascular restriction levels is crucial before engaging in BFR exercise.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Gomes, M, Fitas, A, Santos, P, Pezarat-Correia, P, and Mendonca, GV. Validation of a single session protocol to determine the load-velocity profile and one-repetition maximum for the back squat ...exercise. J Strength Cond Res 38(6): 1013-1018, 2024-We investigated whether a single session of absolute incremental loading is valid to obtain the individual load-velocity profile (LVP) and 1 repetition maximum (1RM) for the free-weight parallel back squat. Twenty strength-trained male subjects completed 3 testing sessions, including a baseline 1RM session and 2 LVP sessions (LVP rel based on incremental relative loads and LVP abs based on absolute load increments until 1RM). The 1RM load was compared between the baseline and LVP abs . The load at zero velocity (load-axis intercept L 0 ), maximal velocity capacity (velocity-axis intercept V 0 ), slope, and area under the load-velocity relationship line (A line ) were compared between the LVP rel and LVP abs using equivalence testing through 2 one-sided t -tests. Measurement accuracy was calculated using the absolute percent error. The 1RM measured at baseline and LVP abs was equivalent and presented a low absolute percent error (1.2%). The following LVP parameters were equivalent between LVP rel and LVP abs : 1RM, L 0 , and A line because the mean difference between sessions was close to zero and the Bland-Altman limits of agreement (1RM:5.3 kg; L 0 :6.8 kg; A line : 9.5 kg·m -1 ·s -1 ) were contained within the a priori defined ± equivalent margins (5% for 1RM and L 0 and 10% for A line ). The aforementioned variables presented a low absolute percent error. However, slope and V 0 were not equivalent between sessions. In conclusion, a single session of absolute incremental loading is a valid approach to obtain the L 0 and A line of the individual LVP and 1RM, and can be used to efficiently track the magnitude of neuromuscular adaptations throughout the training cycles for the free-weight back squat.
To explore if mean concentric velocity (MCV) of the last repetition before set failure differs between free-weight back squat protocols with greater emphasis on metabolic accumulation vs. mechanical ...loading. The between-set and between-day reliability of terminal MCV obtained with these different loading schemes was also determined.
Fifteen healthy male participants (18-30 years) were included. They all were required to exhibit a relative strength ≥ 1.5 times their body mass. MCVs were obtained at one-repetition maximum (1RM) and with two submaximal protocols (metabolic emphasis: three sets of 40%1RM with blood-flow restriction vs. mechanical emphasis: three sets 80%1RM without blood-flow restriction). Participants were instructed to reach maximal intended concentric velocity in each repetition up to failure.
Set failure was achieved at a faster MCV with the metabolic protocol (p < 0.05). The reliability of MCV at failure reached higher values for the metabolic loading scheme. However, while the MCV achieved at failure during the metabolic protocol was systematically higher than the MCV at 1RM (p < 0.05), this was not entirely the case for the mechanical protocol (similar to 1RM MCV during the last sets in both testing days). Finally, the absolute error derived from estimating the MCV at 1RM based on the MCV obtained at set failure with the mechanical protocol was considerably high (≥ 0.05 m/s).
This study indicates that MCV obtained at set failure is dependent on the specificity of the physiological demands of exercise. Thus, MCVs obtained at failure with submaximal loads should not be used to estimate 1RM MCV.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract Mendonca GV, Pereira FD, Fernhall B. Effects of combined aerobic and resistance exercise training in adults with and without Down syndrome. Objective To determine whether adults with Down ...syndrome (DS) could improve their submaximal and peak exercise capacity, as for adults without disabilities, after 12 weeks of combined (aerobic and resistance) exercise training. Design Prospective study comparing the effects of a 12-week combined exercise program on submaximal and peak exercise capacity of adults with and without DS. Setting University facilities. Participants Participants with DS (n=13; mean ± SD age, 36.5±5.5y) and participants without disabilities (n=12; mean age, 38.7±8.3y). Interventions Combined exercise training for 12 weeks. Endurance training was performed 3 days a week for 30 minutes at 65% to 85% of peak oxygen consumption (V o2 peak). Resistance training was prescribed for 2 days a week and consisted of 2 rotations in a circuit of 9 exercises at 12-repetition maximum. Main Outcome Measures Submaximal and maximal graded exercise tests with metabolic and heart rate measurements. Walking economy and V o2 peak were considered the main outcomes. Results Participants with DS and those without disabilities showed similar values for body mass index and relative fat mass at pre- and posttraining periods. Walking economy and V o2 peak overall were lower in participants with DS than participants without disabilities ( P <.05). Training improved walking economy and V o2 peak in participants with DS and those without disabilities ( P <.05); additionally, the magnitude of changes induced by training was similar between groups. Conclusions Overall, a 12-week combined exercise regimen induced gains of similar magnitude between adults with and without DS for submaximal and peak exercise capacity.
PDF
