This study aimed to compare the effects of three resistance training (RT) programs differing in the magnitude of velocity loss (VL) allowed in each exercise set: 10%, 30%, or 45% on changes in ...strength, vertical jump, sprint performance, and EMG variables. Thirty‐three young men were randomly assigned into three experimental groups (VL10%, VL30%, and VL45%; n = 11 each) that performed a velocity‐based RT program for 8 weeks using only the full squat exercise (SQ). Training load (55–70% 1RM), frequency (2 sessions/week), number of sets (3), and inter‐set recovery (4 min) were identical for all groups. Running sprint (20 m), countermovement jump (CMJ), 1RM, muscle endurance, and EMG during SQ were assessed pre‐ and post‐training. All groups showed significant (VL10%: 6.4–58.6%; VL30%: 4.5–66.2%; VL45%: 1.8–52.1%; p < 0.05–0.001) improvements in muscle strength and muscle endurance. However, a significant group × time interaction (p < 0.05) was observed in CMJ, with VL10% showing greater increments (11.9%) than VL30% and VL45%. In addition, VL10% resulted in greater percent change in sprint performance than the other two groups (VL10%: −2.4%; VL30%: −1.8%; and VL45%: −0.5%). No significant changes in EMG variables were observed for any group. RT with loads of 55–70% 1RM characterized by a low‐velocity loss (VL10%) provides a very effective and efficient training stimulus since it yields similar strength gains and greater improvements in sports‐related neuromuscular performance (jump and sprint) compared to training with higher velocity losses (VL30%, VL45%). These findings indicate that the magnitude of VL reached in each exercise set considerably influences the observed training adaptations.
Reply to Drs. Nuzzo and Barry Fregosi, Ralph F; Wagner, Peter D
Journal of applied physiology (1985),
11/2017, Letnik:
123, Številka:
5
Journal Article
A number of resistance training (RT) program variables can be manipulated to maximize muscular hypertrophy. One variable of primary interest in this regard is RT frequency. Frequency can refer to the ...number of resistance training sessions performed in a given period of time, as well as to the number of times a specific muscle group is trained over a given period of time.
We conducted a systematic review and meta-analysis to determine the effects of resistance training frequency on hypertrophic outcomes.
Studies were deemed eligible for inclusion if they met the following criteria: (1) were an experimental trial published in an English-language refereed journal; (2) directly compared different weekly resistance training frequencies in traditional dynamic exercise using coupled concentric and eccentric actions; (3) measured morphologic changes via biopsy, imaging, circumference, and/or densitometry; (4) had a minimum duration of 4 weeks; and (5) used human participants without chronic disease or injury. A total of ten studies were identified that investigated RT frequency in accordance with the criteria outlined.
Analysis using binary frequency as a predictor variable revealed a significant impact of training frequency on hypertrophy effect size (P = 0.002), with higher frequency being associated with a greater effect size than lower frequency (0.49 ± 0.08 vs. 0.30 ± 0.07, respectively). Statistical analyses of studies investigating training session frequency when groups are matched for frequency of training per muscle group could not be carried out and reliable estimates could not be generated due to inadequate sample size.
When comparing studies that investigated training muscle groups between 1 to 3 days per week on a volume-equated basis, the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week. It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.
The primary objective of this systematic review was to update our previous review on randomized controlled trials (RCTs) of exercise in cancers other than breast or prostate, evaluating: 1) the ...application of principles of exercise training within the exercise prescription; 2) reporting of the exercise prescription components (i.e., frequency, intensity, time, and type (FITT)); and 3) reporting of participant adherence to FITT. A secondary objective was to examine whether reporting of these interventions had improved over time.
MEDLINE, EMBASE, CINAHL and SPORTDiscus databases were searched from 2012 to 2020. Eligible studies were RCTs of at least 4 weeks of aerobic and/or resistance exercise that reported on physiological outcomes relating to exercise (e.g., aerobic capacity, muscular strength) in people with cancer other than breast or prostate.
Eighty-six new studies were identified in the updated search, for a total of 107 studies included in this review. The principle of specificity was applied by 91%, progression by 32%, overload by 46%, initial values by 72%, reversibility by 7% and diminishing returns by 5%. A significant increase in the percentage of studies that appropriately reported initial values (46 to 80%, p < 0.001) and progression (15 to 37%, p = 0.039) was found for studies published after 2011 compared to older studies. All four FITT prescription components were fully reported in the methods in 58% of all studies, which was higher than the proportion that fully reported adherence to the FITT prescription components in the results (7% of studies). Reporting of the FITT exercise prescription components and FITT adherence did not improve in studies published after 2011 compared to older studies.
Full reporting of exercise prescription and adherence still needs improvement within exercise oncology RCTs. Some aspects of exercise intervention reporting have improved since 2011, including the reporting of the principles of progression and initial values. Enhancing the reporting of exercise prescriptions, particularly FITT adherence, may provide better context for interpreting study results and improve research to practice translation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT
Introduction: It has not been established whether progressive resistance training (PRT) and aerobic training (AT) are feasible and efficient in myasthenia gravis (MG). Methods: Fifteen ...subjects with generalized MG (Myasthenia Gravis Foundation of America (MGFA) clinical classification II–IV) were randomly assigned to 20 training sessions during 8 weeks of either PRT or AT. Feasibility was evaluated based on adherence, drop‐out rate, adverse events, and Quantitative Myasthenia Gravis (QMG) score. Results: Twelve subjects (MGFA II, n = 11; MGFA III, n=1) completed the intervention with a mean adherence of 95 % ± 8. One dropout (PRT) could potentially be related to PRT. Both groups reported adverse events, including bulbar symptoms (n = 2) and increased fatigue (n = 3), but no change in QMG score was observed in either group. The PRT group showed increases in maximal strength and functional capacity. Conclusions: Eight weeks of moderate to high intensity AT and PRT were feasible for most patients with mild MG. Maximal strength and functional capacity increased in the PRT group. Muscle Nerve 56: 700–709, 2017
The increase and decrease in steady-state isometric force following active muscle lengthening and shortening are referred to as residual force enhancement (RFE) and force depression (FD), ...respectively. The RFE and FD states are associated with decreased (activation reduction; AR) and increased (activation increase; AI) neuromuscular activity, respectively. Although the mechanisms have been discussed over the last 60 years, no studies have systematically investigated the modifiability of RFE and FD with training. The purpose of the present study was to determine whether RFE and FD could be modulated through eccentric and concentric biased resistance training. Fifteen healthy young adult men (age: 24 ± 2 yr, weight: 77 ± 8 kg, height: 178 ± 5 cm) underwent 4 wk of isokinetic dorsiflexion training, in which one leg was trained eccentrically (-25°/s) and the other concentrically (+25°/s) over a 50° ankle excursion. Maximal and submaximal (40% maximum voluntary contraction) steady-state isometric torque and EMG values following active lengthening and shortening were compared to purely isometric values at the same joint angles and torque levels. Residual torque enhancement (rTE) decreased by ~36% after eccentric training ( P < 0.05) and increased by ~89% after concentric training ( P < 0.05), whereas residual torque depression (rTD), AR, AI, and optimal angles for torque production were not significantly altered by resistance training ( P ≥ 0.05). It appears that rTE, but not rTD, for the human ankle dorsiflexors is differentially modifiable through contraction type-dependent resistance training. NEW & NOTEWORTHY The history dependence of force production is a property of muscle unexplained by current cross bridge and sliding filament theories. Whether a muscle is actively lengthened (residual force enhancement; RFE) or shortened (force depression) to a given length, the isometric force should be equal to a purely isometric contraction-but it is not! In this study we show that eccentric training decreased RFE, whereas concentric training increased RFE and converted all nonresponders (i.e., not exhibiting RFE) into responders.
Abstract Objectives To quantify the change in effect sizes, for selected clinical outcome measures, in people with heart failure, from resistance exercise, either in isolation, or in combination with ...aerobic training. Background Most exercise training data in heart failure, relates to aerobic exercise, we sought to provide current evidence for the benefits of resistance training in this population. Methods We conducted a MEDLINE search (1985 to May 1, 2016), for exercise based rehabilitation trials in heart failure, using search terms ‘resistance training, combined training, left ventricular dysfunction, peak VO2 , cardio-myopathy and systolic heart dysfunction’. Results The 27 included studies provided a total of 2321 participants, 1172 in an intervention and 1149 in either sedentary controls or aerobic exercise only groups, producing over 31,263 patient-hours of training. Mortality, hospitalization, resting blood pressure and Left ventricular fraction were all unchanged with resistance or combined aerobic and resistance training. Peak VO2 was improved in combined exercise vs. control MD of 1.43 ml·kg − 1 ·min − 1 (95% CI 0.63, 2.23, p = 0.0004; and in resistance vs. control MD 3.99 ml·kg − 1 ·min − 1 (95% CI 1.47, 6.51, p = 0.002). Quality of Life (MLwHFQ) was improved in combined vs. control MD − 8.31 (95% CI − 14.3, − 2.33, p = 0.006). Six-minute walk distance was improved combined exercise vs. control, MD 13.49 m (95% CI 1.13, 25.84, p = 0.03); and resistance vs. control MD 41.77 m (95% CI 21.90, 61.64, p < 0.0001): SMD 1.25 (95%CI 0.53, 1.98, p = 0.0007). Conclusions Resistance only or combined training improves peak VO2 , quality of life and walking performance in heart failure patients.
Only a few research is available on the effects of home-based exercise training on pre-dialysis chronic kidney disease (CKD) patients. Therefore, we aimed to elucidate the effect of home-based ...exercise therapy on kidney function and arm and leg muscle strength in pre-dialysis CKD patients.
Thirty-six male stage 3-4 pre-dialysis CKD patients (age, 68.7 ± 6.8 years; estimated glomerular filtration rate (eGFR), 39.0 ± 11.6 ml/min/1.73 m
) who were being treated as outpatients were included. The subjects were randomly assigned to an exercise intervention group (Ex group: 18) and a control group (C group: 18). The Ex group wore accelerometer pedometers and were instructed to perform home-based aerobic and resistance exercises, such as brisk walking for 30 min per day, for 12 months. The C group subjects wore accelerometer pedometers but received no exercise therapy guidance; the number of steps covered during normal daily activities was recorded for the C group. The outcome measures were changes in kidney function and handgrip and knee extension muscle strength. Values at the baseline (T1) and 12 months later (T2) were compared.
There were no significant differences in baseline characteristics between the two groups; however, the C group was more physically active than the Ex group. Eight subjects dropped out, and 28 subjects (14 in each group) were included in the final analysis. Physical activity increased significantly only in the Ex group. Grip strength (F = 7.0, p = 0.01) and knee extension muscle strength (F = 14.3, p < 0.01) were found to improve only in the Ex group. Further, the changes in eGFR were not significantly different between the two groups (F = 0.01, p = 0.93).
Home-based exercise therapy for pre-dialysis CKD patients was feasible and improved arm and leg muscle strength without affecting kidney function.
UMIN Clinical Trials Registry ( UMIN000005091 ). Registered 2/15/2011.
INTRODUCTIONLoss of mitochondrial competency is associated with several chronic illnesses. Therefore, strategies that maintain or increase mitochondrial function will likely be of benefit in numerous ...clinical settings. Endurance exercise has long been known to increase mitochondrial function in the skeletal muscle. Comparatively little is known regarding the effect of resistance exercise training (RET) on skeletal muscle mitochondrial respiratory function.
PURPOSEThe purpose of the current study was to determine the effect of chronic resistance training on skeletal muscle mitochondrial respiratory capacity and function.
METHODSHere, we studied the effect of a 12-wk RET program on skeletal muscle mitochondrial function in 11 young healthy men. Muscle biopsies were collected before and after the 12-wk training program, and mitochondrial respiratory capacity was determined in permeabilized myofibers by high-resolution respirometry.
RESULTSRET increased lean body mass and quadriceps muscle strength by 4% and 15%, respectively (P < 0.001). Coupled mitochondrial respiration supported by complex I, and complex I and II substrates increased by 2- and 1.4-fold, respectively (P < 0.01). The ratio of coupled complex I-supported respiration to maximal respiration increased with RET (P < 0.05), as did complex I protein abundance (P < 0.05), whereas the substrate control ratio for succinate was reduced after RET (P < 0.001). Transcripts responsible for proteins critical to electron transfer and NAD production increased with training (P < 0.05), whereas transcripts involved in mitochondrial biogenesis were unaltered.
CONCLUSIONSCollectively, 12 wk of RET resulted in qualitative and quantitative changes in skeletal muscle mitochondrial respiration. This adaptation was accompanied by modest changes in mitochondrial proteins and transcript expression. RET seems to be a means to augment the respiratory capacity and intrinsic function of skeletal muscle mitochondria.
Purpose
Investigate the acute and short-term (i.e., 24 h) effects of traditional (TRAD), superset (SS), and tri-set (TRI) resistance training protocols on perceptions of intensity and physiological ...responses.
Methods
Fourteen male participants completed a familiarisation session and three resistance training protocols (i.e., TRAD, SS, and TRI) in a randomised-crossover design. Rating of perceived exertion, lactate concentration (Lac), creatine kinase concentration (CK), countermovement jump (CMJ), testosterone, and cortisol concentrations was measured pre, immediately, and 24-h post the resistance training sessions with magnitude-based inferences assessing changes/differences within/between protocols.
Results
TRI reported
possible
to
almost certainly
greater efficiency and rate of perceived exertion, although session perceived load was
very likely
lower. SS and TRI had
very likely
to
almost certainly
greater lactate responses during the protocols, with changes in CK being
very likely
and
likely
increased at 24 h, respectively. At 24-h post-training, CMJ variables in the TRAD protocol had returned to baseline; however, SS and TRI were still
possibly
to
likely
reduced.
Possible
increases in testosterone immediately post SS and TRI protocols were reported, with SS showing
possible
increases at 24-h post-training. TRAD and SS showed
almost certain
and
likely
decreases in cortisol immediately post, respectively, with TRAD reporting
likely
decreases at 24-h post-training.
Conclusions
SS and TRI can enhance training efficiency and reduce training time. However, acute and short-term physiological responses differ between protocols. Athletes can utilise SS and TRI resistance training, but may require additional recovery post-training to minimise effects of fatigue.
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