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Purpose: The purpose of this study was to explore whether offset loading in the barbell squat altered ground-reaction force (GRF) and muscle activation in the dominant (D) and nondominant (ND) lower limb compared to traditional squats. Methods: Twelve well-trained men (age 26.4 [3.2] y; 10.3 [1.9] y experience) performed 3 sets of 10 repetitions at 60% of their previously measured 1-repetition maximum. Sets were quasi-randomized between traditional loading (TDL), dominant-side offset loading (OS-D), and nondominant-side offset loading (OS-ND). All repetitions were performed on a dual force plate with electromyography sensors on the prime mover muscles of the squat. GRF symmetry was assessed using the symmetry index (SI) to determine the direction (D [+] or ND [−]) and magnitude (%) of the asymmetry. Finally, the first 3 and final 3 repetitions of each set were compared for compensatory changes in symmetry. Results: OS-D induced a significant change in limb SI relative to TDL (5.21% vs 1.44%; P =.011); however, no significant difference in limb SI was seen between TDL and OS-ND (−0.66% vs 1.44%; P =.278). No asymmetries between D and ND muscle activation were present in any condition. TDL and OS-D squats exhibited significant improvements in limb SI between the first 3 and final 3 repetitions (P =.035 and.011, respectively); however, no such improvement was seen in OS-ND. Conclusions: OS-D is capable of significantly altering GRF limb SI in a bilateral squat; however, OS-ND appears to exhibit no GRF or electromyography effects relative to TDL. Thus, the results of this study do not support the use of OS-ND in the pursuit of strengthening a weaker limb, suggesting that unilateral training may be a preferred mode of exercise for this desired outcome. [ABSTRACT FROM AUTHOR]

Jenkins, NDM, Miramonti, AA, Hill, EC, Smith, CM, Cochrane-Snyman, KC, Housh, TJ, and Cramer, JT. Mechanomyographic amplitude is sensitive to load-dependent neuromuscular adaptations in response to resistance training. J Strength Cond Res 35(11): 3265–3269, 2021—We examined the sensitivity of the mechanomyographic amplitude (MMGRMS) and frequency (MMGMPF) vs. torque relationships to load-dependent neuromuscular adaptations in response to 6 weeks of higher- vs. lower-load resistance training. Twenty-five men (age = 22.8 ± 4.6 years) were randomly assigned to either a high- (n = 13) or low-load (n = 12) training group and completed 6 weeks of leg extension resistance training at 80 or 30% 1RM. Before and after 3 and 6 weeks of training, mechanomyography signals were recorded during isometric contractions at target torques equal to 10–100% of the subjects' baseline maximal strength to quantify MMGRMS and MMGMPF vs. torque relationships. MMGRMS decreased from Baseline to weeks 3 and 6 in the high-load, but not low-load group, and was dependent on the muscle and intensity of contraction examined. Consequently, MMGRMS was generally lower in the high- than low-load group at weeks 3 and 6, and these differences were most apparent in the vastus lateralis (VL) and rectus femoris muscles at higher contraction intensities. MMGMPF was greater in the high- than low-load training group independent of time or muscle. The MMGRMS vs. torque relationship was sensitive to load-dependent, muscle-specific neuromuscular adaptations and suggest reductions in neuromuscular activation to produce the same absolute submaximal torques after training with high, but not low loads. [ABSTRACT FROM AUTHOR]

The purpose of this study was to describe the ... responses relative to ... peak at 4 different intensities within the severe domain and, based on the ?? responses, identify intensity zones above critical velocity (CV). Twelve runners (mean ± SD age = 23.2 ± 3.0 years) performed an incremental treadmill test (ITT) to exhaustion to determine the ... peak and velocity associated with ... peak (... peak). Critical velocity was determined from 4 exhaustive, constant velocity, randomly ordered treadmill runs (V1, V2, V3, and V4; V1 = highest, V4 = lowest). The ... responses were recorded during each of the constant velocity runs. Mean differences among ... peak values from the ITT and the highest value recorded during the constant velocity runs were examined. The ... values at exhaustion for V1 (3.32 ± 0.10 L·min-1, p = 0.15) and V2 (3.27 ± 0.91 L·min-1, p = 0.13) were not significantly different from ... peak (3.39 ± 0.96 L·min-1) from the ITT. The ... values at exhaustion for V3 (3.18 ± 0.88 L·min-1; p = 0.007) and V4 (3.09 ± 0.86 L·min-1; p = 0.003), however, were significantly less than the ... peak from the ITT. There were intensity-dependent ... responses above CV. Based on these findings, we have hypothesized 3 intensity zones (first severe intensity zone [SIZ1], second severe intensity zone [SIZ2], and extreme intensity zone [EIZ]) within the severe and extreme domains, which are characterized by specific ... responses and may be used to design programs that maximize aerobic performance adaptations. [ABSTRACT FROM AUTHOR]

The verification phase is becoming the norm for confirming V̇O2max during a graded exercise test (GXT), but the use of such testing in untrained participants in the heat remains unknown. Purpose: This study aimed to assess the V̇O2 uptake obtained during a GXT and subsequent verification phase in untrained participants in a hot environment. Methods: Twelve sedentary males completed a GXT followed by a biphasic supramaximal-load verification phase in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a temperate chamber and lasted until gastrointestinal temperature returned to baseline. Results: Mean verification phase V̇O2max (37.8 ± 4.3 mL·kg−1·min−1) was lower than GXT (39.8 ± 4.1 mL·kg−1·min−1; P = 0.03) and not statistically equivalent. Using an individualized analysis approach, only 17% (2/12) of participants achieved a V̇O2 plateau during the GXT. Verification phase confirmed GXT V̇O2max in 100% of participants, whereas the traditional and the new age-dependent secondary V̇O2max criteria indicated GXT V̇O2max achievement at much lower rates (8/12 [67%] vs 7/12 [58%], respectively). Correlational indices between GXT and verification phase V̇O2max were strong (intraclass correlation coefficient = 0.95, r = 0.86), and Bland–Altman analysis revealed a low mean bias of −2.1 ± 1.9 mL·kg−1·min−1 and 95% limits of agreement (−5.8 to 1.7 mL·kg−1·min−1). Conclusions: Very few untrained males achieved a V̇O2 plateau during GXT in the heat. When conducting GXT in a hot condition, the verification phase remains a valuable addition to confirm V̇O2max in untrained males. [ABSTRACT FROM AUTHOR]

Verification tests to confirm graded exercise test (GXT) V˙O2max are growing in popularity, but the validity and reliability of such testing in the heat remains unknown. Purpose: This study aimed to evaluate the validity and reliability of a verification test to confirm GXT V˙O2max in a hot environment. Methods: Twelve recreationally trained cyclists completed a two-test protocol that included a GXT progressing 20 W·min−1 followed by a biphasic supramaximal-load verification test (1 min at 60% increasing to 110% maximal GXT wattage until failure) in a hot environment (39°C, 32% relative humidity). Rest between tests occurred in a thermoneutral room and was anchored to the duration required for gastrointestinal temperature to return to baseline. Results: Mean verification test V˙O2max (51.3 ± 8.8 mL·kg−1·min−1) was lower than GXT (55.9 ± 7.6 mL·kg−1·min−1, P = 0.02). Verification tests confirmed GXT V˙O2max in 92% of participants using individual analysis thresholds. Bland–Altman analysis revealed a sizable mean bias (−4.6 ± 4.9 mL·kg−1·min−1) with wide 95% limits of agreement (−14.0 to 5.0 mL·kg−1·min−1) across a range of V˙O2max values. The high coefficient of variation (9.6%) and typical error (±3.48 mL·kg−1·min−1) indicate potential issues of test–retest reliability in the heat. Conclusions: Verification testing in a hot condition confirmed GXT V˙O2max in virtually all participants, indicating robust utility. To enhance test–retest reliability in this environment, protocol recommendations for work rate and recovery between tests are provided. [ABSTRACT FROM AUTHOR]