Vigorous intensity heart rate-clamp exercise does not elicit recommended oxygen consumption rates.

Purpose: This study examined the power output adjustments and subsequent shifts in metabolic (V̇O) demands as well as minute ventilation ( ), respiratory rate (RR), and rating of perceived exertion (RPE) responses during vigorous intensity (77-95% HR) heart rate (HR)-clamp cycle ergometry.

Methods: Fifteen males (mean ± SD age = 25.9 ± 4.

Examination of sex differences in fatigability and neuromuscular responses during continuous, maximal, isometric leg extension.

This study examined sex-related differences in fatigability and neuromuscular responses using surface electromyographic (sEMG) and mechanomyographic (sMMG) amplitude (AMP) and frequency (MPF) during fatiguing, maximal, bilateral isometric leg extensions.Twenty recreationally active males and females with resistance training experience performed continuous, maximal effort, bilateral isometric leg extensions until their force reduced by 50%. Linear mixed effect models analyzed patterns of force, sEMG, and sMMG AMP and MPF responses in the dominant limb.

The effects of sex and contraction intensity on fatigability and muscle oxygenation in trained individuals.

Fatigability varies depending on sex and contraction intensity during sustained exercise. This study examined the responses of time to task failure (TTF), performance fatigability (PF), and muscle oxygenation (SmO) in males and females during isometric handgrip holds to failure (HTF) at 30% and 60% maximum voluntary isometric contraction (MVIC). Males ( = 12) and females ( = 12) performed a pre-MVIC, handgrip HTF at randomly ordered percentages of MVIC (either 30% or 60%), followed by a post-MVIC on the dominant arm.

The effects of low vs. high rating of perceived exertion clamp exercise on performance, neuromuscular, and muscle oxygen saturation responses in females.

Purpose: This study examined the time course of changes in force, relative to critical force (CF), electromyographic amplitude (EMG AMP), neuromuscular efficiency (NE), and muscle oxygen saturation (SmO), as well as time to task failure (TTF) and performance fatigability (PF) during isometric handgrip holds to failure (HTF) anchored to the rating of perceived exertion (RPE) at 3 and 7.

Methods: Ten females completed pre-test maximal voluntary isometric contractions (MVICs), submaximal HTF at four percentages of MVIC, an HTF at RPE = 3 and 7, and post-test MVICs. Analyses included paired samples t-tests, repeated measures ANOVAs and planned comparisons.

Comparison of Force, Neuromuscular, and Metabolic Responses During Sustained, Isometric Handgrip Holds to Failure Anchored to Low and High Perceptual Intensities in Men: An Exploratory Study.

Kwak, M, Succi, PJ, Benitez, B, Mitchinson, C, Samaan, MA, Abel, MG, and Bergstrom, HC. Comparison of force, neuromuscular, and metabolic responses during sustained, isometric handgrip holds to failure anchored to low and high perceptual intensities in men: An exploratory study. J Strength Cond Res 38(8): e405-e416, 2024-This study examined the responses of force alterations, relative to critical force (CF), neuromuscular parameters, and muscle oxygenation (SmO2) for isometric handgrip holds to failure (HTF) anchored to ratings of perceived exertion (RPE) of 3 and 7.

Force and Neuromuscular Responses During a Handgrip Hold to Failure Anchored to a Moderate Perceptual Intensity in Males.

Objectives: The current study investigated performance fatigability (PF) and time course of changes in force, electromyographic amplitude (EMG AMP) and frequency (EMG MPF), and neuromuscular efficiency (NME) during a sustained, isometric, handgrip hold to failure (HTF) using the rating of perceived exertion (RPE)-Clamp Model.

Methods: Twelve males performed a handgrip HTF anchored to RPE=5. The time to task failure (T), force (N), EMG AMP and MPF, and NME (normalized force/ normalized EMG AMP) were recorded.

No sex differences in time-to-task failure and neuromuscular patterns of response during submaximal, bilateral, isometric leg extensions.

Background: In general, it has been suggested that females are more fatigue-resistant than males, with the magnitude of difference being most pronounced during low-intensity sustained contractions. However, the mechanisms for the apparent sex difference have not yet been fully elucidated in the literature. This study aimed to examine sex-related differences in fatigability and patterns of neuromuscular responses for surface electromyographic (sEMG) and mechanomyographic (sMMG) amplitude and frequency (MPF) characteristics during a sustained submaximal bilateral, isometric leg extension muscle action.

Metabolic and Perceptual Responses to Constant Heart Rate Exercise at Vigorous Intensities in Women.

Purpose: This study quantified the metabolic demands (oxygen uptake (V̇O 2 )), power output adjustments, changes in the V̇O 2 /power output ratio, and perceptual responses (rating of perceived exertion (RPE)) during constant heart rate (HR) exercise performed within the vigorous intensity range (77%-95% HR peak ).

Methods: Twelve women (mean ± SD age, 22 ± 4 yr) performed a graded exercise test to exhaustion to determine peak parameters, and three randomly ordered, constant HR trials to exhaustion or for 60 min at the lower (HR L = 77% HR peak ), middle (HR M = 86% HR peak ), and higher (HR H = 95% HR peak ) end of the vigorous intensity range. Time course of changes and patterns of responses were examined for V̇O 2 , power output, V̇O 2 /power output, and RPE for the composite and for each subject.

Analysis of Individual V˙O Responses during a Cardiopulmonary Exercise Test and the Verification Phase in Physically Active Women.

This study aimed to investigate the test-retest reliability, mean, and individual responses in the measurement of maximal oxygen consumption (V˙O) during a cardiopulmonary exercise test (CPET) and the verification phase during cycle ergometry in women. Nine women (22 ± 2 yrs, 166.0 ± 4.

Unilaterally Induced Quadriceps Fatigue during Sustained Submaximal Isometric Exercise Does Not Alter Contralateral Leg Extensor Performance.

This study investigated the effects of fatiguing unilateral exercise on the ipsilateral, exercised, and contralateral, non-exercised limb's post-exercise performance in males and females. Ten males and ten females performed a fatiguing, unilateral isometric leg extension at 50% maximal voluntary isometric contraction (MVIC) force. Prior to and immediately after the fatiguing tasks, MVICs were performed for the exercised and non-exercised limb, with surface electromyographic (sEMG) and mechanomyography (sMMG) amplitude (AMP) and mean power frequency (MPF) recorded from each limb's vastus lateralis.

Sustainability and perceptual responses during handgrip holds to failure at two fatigue thresholds.

Purpose: Critical force (CF) provides an estimate of the asymptote of the force-duration curve and the physical working capacity at the rating of perceived exertion (PWC) estimates the highest force that can be sustained without an increase in perceived exertion. Handgrip-related musculoskeletal disorders and injuries derived from sustained or repetitive motion-induced muscle fatigue are prevalent in the industrial workforce. Thus, it is important to understand the physiological mechanisms underlying performance during handgrip specific tasks to describe individual work capacities.

Electromyographic and mechanomyographic responses of the biceps brachii during concentric and eccentric muscle actions to failure at high and low relative loads.

Purpose: This study examined neuromuscular responses of the biceps brachii (BB) for concentric and eccentric muscle actions during bilateral, dynamic constant external resistance (DCER), reciprocal forearm flexions and extensions to failure at high (80% 1 repetition maximum [1RM]) and low (30% 1RM) relative loads.

Methods: Nine women completed 1RM testing and repetitions to failure (RTF) at 30 and 80% 1RM. Electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) signals were measured from the BB.

Load-Specific Performance Fatigability, Coactivation, and Neuromuscular Responses to Fatiguing Forearm Flexion Muscle Actions in Women.

Benitez, B, Dinyer-McNeeley, TK, McCallum, L, Kwak, M, Succi, PJ, and Bergstrom, HC. Load-specific performance fatigability, coactivation, and neuromuscular responses to fatiguing forearm flexion muscle actions in women. J Strength Cond Res 37(4): 769-779, 2023-This study examined the effects of fatiguing, bilateral, dynamic constant external resistance (DCER) forearm flexion on performance fatigability, coactivation, and neuromuscular responses of the biceps brachii (BB) and triceps brachii (TB) at high (80% 1 repetition maximum [1RM]) and low (30% 1RM) relative loads in women.

The Minimal Difference as an Individual Threshold to Examine the Utility of a Verification Bout in Determining V̇O 2max.

Purpose: A square-wave verification bout to confirm maximal oxygen uptake (V̇O 2max ) from a graded exercise test (GXT) has been recommended based on mean responses. This study used the test-retest reliability, mean, and individual differences between the highest V̇O 2 from the GXT (V̇O 2GXT ) and verification bout (V̇O 2verification ) to examine the efficacy of a verification bout in the determination of O 2max in healthy, recreationally trained, well-motivated men.

Methods: Ten men (24 ± 4 yr) completed a GXT on a cycle ergometer followed by a submaximal verification bout to determine V̇O 2GXT and V̇O 2verification .

Methodological considerations for the determination of VO in healthy men.

Purpose: A square-wave verification bout to confirm maximal oxygen uptake ([Formula: see text]O) from a graded exercise test (GXT) has been recommended. This study ascertained if a verification bout is necessary to determine [Formula: see text]O in moderately trained men.

Methods: Ten men (24 ± 4 years) completed familiarization and two treadmill GXTs, followed by a submaximal verification bout to determine [Formula: see text]O and [Formula: see text]O (highest [Formula: see text]O from each testing method).

Accuracy of Predicting One-Repetition Maximum from Submaximal Velocity in The Barbell Back Squat and Bench Press.

This study examined the accuracy of predicting a free-weight back squat and a bench press one-repetition maximum (1RM) using both 2- and 4-point submaximal average concentric velocity (ACV) methods. Seventeen resistance trained men performed a warm-up and a 1RM test on the squat and bench press with ACV assessed on all repetitions. The ACVs during the warm-up closest to 1.

Methods for Controlling and Reporting Resistance Training Proximity to Failure: Current Issues and Future Directions.

Resistance training variables such as volume, load, and frequency are well defined. However, the variable proximity to failure does not have a consistent quantification method, despite being defined as the number of repetitions in reserve (RIR) upon completion of a resistance training set. Further, there is between-study variability in the definition of failure itself.

Integrated and diurnal indices of maternal pregnancy cortisol in relation to sex-specific parasympathetic responsivity to stress in infants.

Maternal hypothalamic-pituitary-adrenal axis activity may prenatally program sex-specific stress-response pathways. We investigated associations between maternal cortisol during pregnancy and infant parasympathetic responsivity to stress among 204 mother-infant pairs. Cortisol indices included 3rd trimester hair cortisol, as well as diurnal slope and area under the curve, derived from saliva samples collected during pregnancy.

Temporal coordination between actions and sound during sequence production.

Delayed auditory feedback (DAF) causes asynchronies between perception and action that disrupt sequence production. Different delay lengths cause differing amounts of disruption that may reflect the phase location of feedback onsets relative to produced inter-response intervals, or the absolute temporal separation between actions and sounds. Two experiments addressed this issue by comparing the effects of traditional DAF, which uses a constant temporal separation, with delays that adjust temporal separation to maintain the phase location of feedback onsets within inter-response intervals.