Examination of Resistance Settings Based on Body Weight for the 3-Minute All-Out Critical Power Test

International Journal of Exercise Science 11(4): 585-597, 2018. There are conflicting suggestions regarding the most valid resistance (3-5% of body weight) to use for the critical power (CP) 3-min all-out (CP3min) test to estimate CP and anaerobic work capacity (AWC). The purpose of this study was to determine if the CP and AWC estimates from the CP3min test were affected by the percentage of body weight used to set the resistance on a Monark cycle ergometer. Ten recreationally trained participants (mean ± SD: Age: 22.2 ± 2.2 yrs.) completed the CP3min test at resistances of 4.5% (CP4.5%) and 3% (CP3%) of body weight to determine the CP and AWC. There were no significant differences between the CP4.5% (167 ± 34 W) and CP3% (156 ± 36 W) estimates. The AWC3% (5.6 ± 2.5 kJ) estimates were significantly lower than the AWC4.5% (9.0 ± 4.0 kJ).The CP and AWC estimates from the CP4.5% were consistent with values reported in the literature, however, the AWC estimate from the CP3% was lower than typically reported. These findings suggested that a resistance set at 3% of body weight for the CP3min test may be too low to accurately estimate AWC, but 3% and 4.5% resulted in the same estimation of CP. Thus, the principal finding of this study was that a resistance of 4.5% of body weight for CP3-min in recreationally trained participants resulted in more accurate estimates of AWC, compared to a resistance of 3%, and supports the use of 4.5% body weight resistance to measure both CP and AWC

Comparisons of the Metabolic Intensities at Heart Rate, Gas Exchange, and Ventilatory Thresholds

International Journal of Exercise Science 13(2): 455-469, 2020. PURPOSE: This study compared the O2corresponding to the critical heart rate (CHRO2) and the physical working capacity at the heart rate fatigue threshold (PWChrtO2) to the gas exchange threshold (GET), ventilatory threshold (VT), and respiratory compensation point (RCP). METHODS: Nine runners (mean ±SD, age 23 ±3 years) completed an incremental test on a treadmill to determine O2peak, GET, VT, and RCP. The CHRO2and PWChrtO2were determined from 4 separate constant velocity treadmill runs to exhaustion and HR and time to exhaustion were recorded. Differences among the thresholds were examined with a one-way repeated measures ANOVA (p≤ 0.05). RESULTS: The GET (38.44 mL×kg-1×min-1, 78%O2peak), VT (37.36 mL×kg-1×min-1, 76%O2peak), and PWChrtO2 (38.26 mL×kg-1×min-1, 77%O2peak) were not different, but were lower than the RCP (44.70 mL×kg-1×min-1, 90%O2peak;p= 0.010, p\u3c 0.001,p= 0.001, respectively). The CHRO2(40.09 mL×kg-1×min-1, 81%O2peak) was not different from the GET (p= 1.000), VT (p= 0.647), PWChrtO2(p =1.000), or RCP (p= 0.116). CONCLUSIONS: These results indicated that the initial metabolic intensities at CHR and PWChrtlie within the heavy and moderate intensity domains, respectively. Therefore, the PWChrtmay provide a relative intensity more appropriate for untrained populations, while the CHR may be more appropriate for more trained populations

Applications of the Critical Power Model to Dynamic Constant External Resistance Exercise: A Brief Review of the Critical Load Test

The study and application of the critical power (CP) concept has spanned many decades. The CP test provides estimates of two distinct parameters, CP and W0 , that describe aerobic and anaerobic metabolic capacities, respectively. Various mathematical models have been used to estimate the CP and W0 parameters across exercise modalities. Recently, the CP model has been applied to dynamic constant external resistance (DCER) exercises. The same hyperbolic relationship that has been established across various continuous, whole-body, dynamic movements has also been demonstrated for upper-, lower-, and whole-body DCER exercises. The asymptote of the load versus repetition relationship is defined as the critical load (CL) and the curvature constant is L0 . The CL and L0 can be estimated from the same linear and non-linear mathematical models used to derive the CP. The aims of this review are to (1) provide an overview of the CP concept across continuous, dynamic exercise modalities; (2) describe the recent applications of the model to DCER exercise; (3) demonstrate how the mathematical modeling of DCER exercise can be applied to further our understanding of fatigue and individual performance capabilities; and (4) make initial recommendations regarding the methodology for estimating the parameters of the CL test

Muscular Performance and Neuromuscular Fatigue are not Sex-Dependent During Low-Load Fatiguing Bilateral Leg Extension Exercise

Purpose. This study examined the sex-related differences in muscular performance and neuromuscular (electromyographic [EMG] and mechanomyographic [MMG] amplitude [AMP] and mean power frequency [MPF]) responses during fatiguing leg extension repetitions performed at the critical load (CL). Methods. Eleven men and nine women completed one-repetition maximum (1RM) testing, repetitions to failure at 50, 60, 70, and 80% 1RM to determine CL, and repetitions to failure at CL, on separate days. The EMG and MMG, AMP and MPF signals and number of repetitions completed were recorded. Results. There were no sex-dependent responses in the %1RM that corresponded to, the number of repetitions completed at, or the neuromuscular responses during repetitions performed to failure at CL. There were time-dependent responses in EMG AMP from 25-100% of total repetitions completed, respectively. The EMG MPF and MMG MPF demonstrated fatigue-induced decreases from 50-100% and at 100% of total repetitions completed, respectively. There was no change over time for MMG AMP. Conclusions. These findings indicated men and women responded similarly to leg extension exercise performed at the CL. Further, sex-dependent responses to fatiguing exercise may be related to the amount of active muscle mass engaged in exercise and the corresponding afferent feedback that influences peripheral fatigue and central drive during fatiguing tasks

Unilateral Handgrip Holds to Failure Result in Sex-Dependent Contralateral Facilitation

There can be differences in fatigue characteristics between men and women. In some cases, these differences may be manifested in unique strength responses in the fatigued and non-fatigued limbs following a unilateral fatiguing task. PURPOSE: This study examined changes in maximal voluntary isometric contraction (MVIC) force following dominant (Dm) and nondominant (NDm) unilateral, isometric handgrip holds to failure (HTF) for the exercised ipsilateral (IPS) and non-exercised contralateral (CT) limbs. Sex- and hand- (Dm vs NDm) dependent responses in HTF time, performance fatiguability (PF, %D in MVIC) for the exercised IPS limb, as well as changes in MVIC force for the CT limb following the HTF were examined. METHODS: Ten men and 10 women (Age = 22.2 yrs) performed an isometric, HTF at 50% MVIC for the Dm and NDm hand on separate days. Prior to, and immediately after the HTF, a MVIC was performed on the IPS and CT limbs, in a randomized order. A 2 (hand [Dm, NDm]) x 2 (limb [IPS, CON]) x 2 (time [pre-HTF, post-HTF]) x 2 (sex [men, women]) mixed-model ANOVA was used to examine the MVIC force (kg) and a 2 (hand [Dm, NDm]) x 2 (sex [men, women]) mixed-model ANOVA was used to examine time for the HTF. RESULTS: The Dm (130.3 ± 36.8s) HTF (collapsed across sex) was significantly longer (p = 0.002) than the NDm (112.1 ± 34.3s). The men (collapsed across hand) demonstrated IPS (%Δ= 22.9 ± 10.8%) PF and CT facilitation (%Δ= -6.1 ±6.9%) following the HTF, while the women demonstrated differences in PF between the Dm and NDm hands for the IPS (%Δ Dm = 28.0 ± 9.4%; NDm = 32.3% ± 10.1%; p = 0.027), but not the CT limb (%Δ Dm= -1.6 ± 5.7%; NDm = 1.7 ± 5.9%). CONCLUSIONS: Despite the greater fatigue resistance for the Dm compared to the NDm hand, there were no differences in PF for the IPS side for the men, but lesser IPS PF for Dm compared to NDm hand for the women. The cross-over facilitation of the CT limb for men, but not women, following a unilateral, isometric handgrip HTF may be related to post-activation potentiation

Examination of Curcumin and Fenugreek Soluble Fiber Supplementation on Submaximal and Maximal Aerobic Performance Indices

This study examined the effects of curcumin and fenugreek soluble fiber supplementation on the ventilatory threshold (VT) and peak oxygen consumption (VO2 peak). Methods: Forty-five untrained men and women were randomly assigned to one of three supplementation groups: placebo (PLA, n = 13), 500 mg·day−1 CurQfen® (CUR, n = 14), or 300 mg·day−1 fenugreek soluble fiber (FEN, n = 18). Participants completed a maximal graded exercise test on a cycle ergometer to determine the VT and VO2 peak before (PRE) and after (POST) 28 days of daily supplementation. Separate, one-way analyses of covariance (ANCOVAs) were used to examine the between-group differences for adjusted POST VT and VO2 peak values, covaried for the respective PRE-test values. Results: The adjusted POST VT VO2 values for the CUR (mean SD = 1.593 0.157 L·min−1) and FEN (1.597 0.157 L·min−1) groups were greater than (p = 0.039 and p = 0.025, respectively) the PLA (1.465 0.155 L·min−1) group, but the FEN and CUR groups were not different (p = 0.943). There were no differences in the adjusted VO2 peak values (F = 0.613, p = 0.547) among groups. Conclusion: These findings indicated that fenugreek soluble fiber was responsible for the improvements in the submaximal performance index for both CUR and FEN groups

Individual Responses for Muscle Activation, Repetitions, and Volume during Three Sets to Failure of High- (80% 1RM) \u3ci\u3eversus\u3c/i\u3e Low-Load (30% 1RM) Forearm Flexion Resistance Exercise

This study compared electromyographic (EMG) amplitude, the number of repetitions completed, and exercise volume during three sets to failure of high- (80% 1RM) versus low-load (30% 1RM) forearm flexion resistance exercise on a subject-by-subject basis. Fifteen men were familiarized, completed forearm flexion 1RM testing. Forty-eight to 72 h later, the subjects completed three sets to failure of dumbbell forearm flexion resistance exercise with 80% (n = 8) or 30% (n = 7) 1RM. EMG amplitude was calculated for every repetition, and the number of repetitions performed and exercise volume were recorded. During sets 1, 2, and 3, one of eight subjects in the 80% 1RM group demonstrated a significant linear relationship for EMG amplitude versus repetition. For the 30% 1RM group, seven, five, and four of seven subjects demonstrated significant linear relationships during sets 1, 2, and 3, respectively. The mean EMG amplitude responses show that the fatigue-induced increases in EMG amplitude for the 30% 1RM group and no change in EMG amplitude for the 80% 1RM group resulted in similar levels of muscle activation in both groups. The numbers of repetitions completed were comparatively greater, while exercise volumes were similar in the 30% versus 80% 1RM group. Our results, in conjunction with those of previous studies in the leg extensors, suggest that there may be muscle specific differences in the responses to high- versus low-load exercise

The effects of anatabine on non-invasive indicators of muscle damage: a randomized, double-blind, placebo-controlled, crossover study

Background: Anatabine (ANA), a minor tobacco alkaloid found in the Solanaceae family of plants, may exhibit anti-inflammatory activity, which may be useful to aid in recovery from exercise-induced muscle damage. The purpose of this study, therefore, was to examine the effects of ANA supplementation on the recovery of isometric strength and selected non-invasive indicators of muscle damage. Methods: A double-blinded, placebo-controlled, crossover design was used to study eighteen men (mean ± SD age = 22.2 ± 3.1 yrs; body mass = 80.3 ± 15.7 kg) who participated in two randomly-ordered conditions separated by a washout period. The ANA condition consisted of consuming 6–12 mg anatabine per day for 10 days, while testing took place during days 7–10. The placebo (PLA) condition was identical except that the PLA supplement contained no ANA. Maximal voluntary isometric peak torque (PT) of the forearm flexors, arm circumference, hanging joint angle, and subjective pain ratings were measured before (PRE), immediately after (POST), and 24, 48, and 72 h after six sets of 10 maximal, eccentric isokinetic forearm flexion muscle actions. Resting heart rate and blood pressure were measured at PRE and 72 h in each condition. Results: For PT, hanging joint angle, arm circumference, and subjective pain ratings, there were no condition x time (p \u3e 0.05) interactions, there were no main effects for condition (p \u3e 0.05), but there were main effects for time (p \u3c 0.001). There were no condition x time (p \u3e 0.05) interactions and no main effects for condition (p \u3e 0.05) or time (p \u3e 0.05) for blood pressure or resting heart rate. Conclusions: ANA supplementation had no effect on the recovery of muscle strength, hanging joint angle, arm swelling, or subjective pain ratings after a bout of maximal eccentric exercise in the forearm flexors. Therefore, ANA may not be beneficial for those seeking to improve recovery from heavy eccentric exercise. Future studies should examine the effects of ANA on the pro-inflammatory cytokine responses to exercise-induced muscle damage and the chronic low-grade inflammation observed in obese and elderly individuals

Individual Responses for Muscle Activation, Repetitions, and Volume during Three Sets to Failure of High- (80% 1RM) \u3cem\u3eversus\u3c/em\u3e Low-Load (30% 1RM) Forearm Flexion Resistance Exercise

This study compared electromyographic (EMG) amplitude, the number of repetitions completed, and exercise volume during three sets to failure of high- (80% 1RM) versus low-load (30% 1RM) forearm flexion resistance exercise on a subject-by-subject basis. Fifteen men were familiarized, completed forearm flexion 1RM testing. Forty-eight to 72 h later, the subjects completed three sets to failure of dumbbell forearm flexion resistance exercise with 80% (n = 8) or 30% (n = 7) 1RM. EMG amplitude was calculated for every repetition, and the number of repetitions performed and exercise volume were recorded. During sets 1, 2, and 3, one of eight subjects in the 80% 1RM group demonstrated a significant linear relationship for EMG amplitude versus repetition. For the 30% 1RM group, seven, five, and four of seven subjects demonstrated significant linear relationships during sets 1, 2, and 3, respectively. The mean EMG amplitude responses show that the fatigue-induced increases in EMG amplitude for the 30% 1RM group and no change in EMG amplitude for the 80% 1RM group resulted in similar levels of muscle activation in both groups. The numbers of repetitions completed were comparatively greater, while exercise volumes were similar in the 30% versus 80% 1RM group. Our results, in conjunction with those of previous studies in the leg extensors, suggest that there may be muscle specific differences in the responses to high- versus low-load exercise

Electromyographic Responses from the Vastus Medialis during Isometric Muscle Actions

This study examined the electromyographic (EMG) responses from the vastus medialis (VM) for electrodes placed over and away from the innervation zone (IZ) during a maximal voluntary isometric contraction (MVIC) and sustained, submaximal isometric muscle action. A linear electrode array was placed on the VM to identify the IZ and muscle fiber pennation angle during an MVIC and sustained isometric muscle action at 50 % MVIC. EMG amplitude and frequency parameters were determined from 7 bipolar channels of the electrode array, including over the IZ, as well as 10 mm, 20 mm and 30 mm proximal and distal to the IZ. There were no differences between the channels for the patterns of responses for EMG amplitude or mean power frequency during the sustained, submaximal isometric muscle action; however, there were differences between channels during the MVIC. The results of the present study supported the need to standardize the placement of electrodes on the VM for the assessment of EMG amplitude and mean power frequency. Based on the current findings, it is recommended that electrode placements be distal to the IZ and aligned with the muscle fiber pennation angle during MVICs, as well as sustained, submaximal isometric muscle actions