Are incremental exercise relationships between rating of perceived exertion and oxygen uptake or heart rate reserve valid during steady-state exercises?

Background: Rating of perceived exertion (RPE) is considered a valid method for prescribing prolonged aerobic steady-state exercise (SSE) intensity due to its association with physiological indicators of exercise intensity, such as oxygen uptake (V̇O2) or heart rate (HR). However, these associations between psychological and physiological indicators of exercise intensity were found during graded exercise tests (GXT) but are currently used to prescribe SSE intensity even though the transferability and validity of the relationships found during GXT to SSE were not investigated. The present study aims to verify whether (a) RPE-HR or RPE-V̇O2 relations found during GXTs are valid during SSEs, and (b) the duration and intensity of SSE affect these relations. Methods: Eight healthy and physically active males (age 22.6 ± 1.2 years) were enrolled. On the first visit, pre-exercise (during 20 min standing) and maximal (during a GXT) HR and V̇O2 values were measured. Then, on separate days, participants performed 4 SSEs on the treadmill by running at 60% and 80% of the HR reserve (HRR) for 15 and 45 min (random order). Individual linear regressions between GXTs' RPE (dependent variable) and HRR and V̇O2 reserve (V̇O2R) values (computed as the difference between maximal and pre-exercise values) were used to predict the RPE associated with %HRR (RPEHRR) and %V̇O2R (RPEV̇O2R) during the SSEs. For each relation (RPE-%HRR and RPE-%V̇O2R), a three-way factorial repeated measures ANOVA (α = 0.05) was used to assess if RPE (dependent variable) was affected by exercise modality (i.e., RPE recorded during SSE [RPESSE] or GXT-predicted), duration (i.e., 15 or 45 min), and intensity (i.e., 60% or 80% of HRR). Results: The differences between RPESSE and GXT-predicted RPE, which were assessed by evaluating the effect of modality and its interactions with SSE intensity and duration, showed no significant differences between RPESSE and RPEHRR. However, when RPESSE was compared with RPEV̇O2R, although modality or its interactions with intensity were not significant, there was a significant (p = 0.020) interaction effect of modality and duration yielding a dissociation between changes of RPESSE and RPEV̇O2R over time. Indeed, RPESSE did not change significantly (p = 0.054) from SSE of 15 min (12.1 ± 2.0) to SSE of 45 min (13.5 ± 2.1), with a mean change of 1.4 ± 1.8, whereas RPEV̇O2R decreased significantly (p = 0.022) from SSE of 15 min (13.7 ± 3.2) to SSE of 45 min (12.4 ± 2.8), with a mean change of -1.3 ± 1.5. Conclusion: The transferability of the individual relationships between RPE and physiological parameters found during GXT to SSE should not be assumed as shown by the results of this study. Therefore, future studies modelling how the exercise prescription method used (e.g., RPE, HR, or V̇O2) and SSE characteristics (e.g., exercise intensity, duration, or modality) affect the relationships between RPE and physiological parameters are warranted.

Respiratory symptom perception during exercise in patients with heart failure with preserved ejection fraction.

We investigated whether central or peripheral limitations to oxygen uptake elicit different respiratory sensations and whether dyspnea on exertion (DOE) provokes unpleasantness and negative emotions in patients with heart failure with preserved ejection fraction (HFpEF). 48 patients were categorized based on their cardiac output (Q̇c)/oxygen uptake (V̇O2) slope and stroke volume (SV) reserve during an incremental cycling test. 15 were classified as centrally limited and 33 were classified as peripherally limited. Ratings of perceived breathlessness (RPB) and unpleasantness (RPU) were assessed (Borg 0-10 scale) during a 20 W cycling test. 15 respiratory sensations statements (1-10 scale) and 5 negative emotions statements (1-10) were subsequently rated. RPB (Central: 3.5±2.0 vs. Peripheral: 3.4±2.0, p=0.86), respiratory sensations, or negative emotions were not different between groups (p>0.05). RPB correlated (p<0.05) with RPU (r=0.925), "anxious" (r=0.610), and "afraid" (r=0.383). While DOE provokes elevated levels of negative emotions, DOE and respiratory sensations seem more related to a common mechanism rather than central and/or peripheral limitations in HFpEF.

Comparison Between Traditional and Alternated Resistance Exercises on Blood Pressure, Acute Neuromuscular Responses, and Rating of Perceived Exertion in Recreationally Resistance-Trained Men.

ABSTRACT: Corrêa Neto, VG, Silva, DdN, Palma, A, de Oliveira, F, Vingren, JL, Marchetti, PH, da Silva Novaes, J, and Monteiro, ER. Comparison between traditional and alternated resistance exercises on blood pressure, acute neuromuscular responses, and rating of perceived exertion in recreationally resistance-trained men. J Strength Cond Res 38(5): e211-e218, 2024-The purpose of this study was to compare the acute effects of traditional and alternated resistance exercises on acute neuromuscular responses (maximum repetition performance, fatigue index, and volume load), rating of perceived exertion (RPE), and blood pressure (BP) in resistance-trained men. Fifteen recreationally resistance-trained men (age: 26.40 ± 4.15 years; height: 173 ± 5 cm, and total body mass: 78.12 ± 13.06 kg) were recruited and performed all 3 experimental conditions in a randomized order: (a) control (CON), (b) traditional (TRT), and (c) alternated (ART). Both conditions (TRT and ART) consisted of 5 sets of bilateral bench press, articulated bench press, back squat, and Smith back squat exercises at 80% 1RM until concentric muscular failure. The total number of repetitions performed across sets in the bench press followed a similar pattern for TRT and ART, with significant reductions between sets 3, 4, and 5 compared with set 1 (p < 0.05). There was a significant difference for set 4 between conditions with a lower number of repetitions performed in the TRT. The volume load was significantly higher for ART when compared with TRT. TRT showed significant reductions in BP after 10-, 40-, and 60-minute postexercise and when compared with CON after 40- and 60-minute postexercise. However, the effect size illustrated large reductions in systolic BP during recovery in both methods. Thus, it is concluded that both methods reduced postexercise BP.

Self-efficacy, Effort, and Performance Perceptions Enhance Psychological Responses to Strength Training in National Collegiate Athletic Association Division I Athletes.

ABSTRACT: Biscardi, LM, Miller, AD, Andre, MJ, and Stroiney, DA. Self-efficacy, effort, and performance perceptions enhance psychological responses to strength training in National Collegiate Athletic Association Division I athletes. J Strength Cond Res 38(5): 898-905, 2024-This study examined the effect of self-efficacy, effort, and perceived performance on positive well-being (PWB) and psychological distress (PD) following high-intensity resistance training sessions in collegiate student-athletes. An observational field study design was used to collect data before and after resistance training sessions in a 4-week preseason strength training block. A multilevel model assessed day-level and person-level variance in acute PWB and PD. Interaction terms were also tested at the day level. Alpha was set at 0.05. Within a 4-week training block, training session intensity did not predict changes in acute psychological responses. After controlling for an athlete's preexercise psychological state, higher self-efficacy, daily effort, and perceived performance predicted higher PWB and lower PD following training (p < 0.05). Self-efficacy moderated the relationships of daily effort and performance with PD (p < 0.05). When athletes experienced lower self-efficacy, producing a higher effort and perceiving better performance reduced the negative psychological response. These findings highlight the important mediating role of cognitive variables in the acute psychological response to high-intensity resistance training. Coaches should identify and mitigate low cognitive states to facilitate a positive psychological response to resistance training. This strategy promotes a positive psychological response without altering training prescription.

The Effects of Anchoring a Fatiguing Forearm Flexion Task to a High vs. Low Rating of Perceived Exertion on Torque and Neuromuscular Responses.

ABSTRACT: Ortega, DG, Housh, TJ, Smith, RW, Arnett, JE, Neltner, TJ, Schmidt, RJ, and Johnson, GO. The effects of anchoring a fatiguing forearm flexion task to a high versus low rating of perceived exertion on torque and neuromuscular responses. J Strength Cond Res 38(5): e219-e225, 2024-This study examined the torque and neuromuscular responses following sustained, isometric, forearm flexion tasks anchored to 2 ratings of perceived exertion (RPE). Nine men (mean ± SD: age = 21.0 ± 2.4 years; height = 179.5 ± 5.1 cm; body mass = 79.6 ± 11.4 kg) completed maximal voluntary isometric contractions (MVIC) before and after sustained, isometric, forearm flexion tasks to failure anchored to RPE = 2 and RPE = 8. The amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) signal were recorded from the biceps brachii. Normalized torque was divided by normalized EMG AMP to calculate neuromuscular efficiency (NME). A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated-measures analysis of variances was used to compare mean differences for MVIC and normalized neuromuscular parameters. There was no significant difference in TTF between RPE = 2 and RPE = 8 (p = 0.713). The MVIC decreased from pretest to posttest at RPE = 2 (p = 0.009) and RPE = 8 (p = 0.003), and posttest MVIC at RPE = 8 was less than that at RPE = 2 (p < 0.001). In addition, NME decreased from pretest to posttest (p = 0.008). There was no change in normalized EMG AMP or EMG MPF (p > 0.05). The current findings indicated that torque responses were intensity specific, but TTF and neuromuscular responses were not. Furthermore, normalized EMG AMP and EMG MPF remained unchanged but NME decreased, likely due to peripheral fatigue and excitation-contraction coupling failure. Thus, this study provides information regarding the neuromuscular responses and mechanisms of fatigue associated with tasks anchored to RPE, which adds to the foundational understanding of the relationship between resistance exercise and the perception of fatigue.

Performance and perceived fatigability across the intensity spectrum: role of muscle mass during cycling.

The role of muscle mass in modulating performance and perceived fatigability across the entire intensity spectrum during cycling remains unexplored. We hypothesized that at task failure (Tlim), muscle contractile function would decline more following single- (SL) versus double-leg (DL) cycling within severe and extreme intensities, but not moderate and heavy intensities. After DL and SL ramp-incremental tests, on separate days, 11 recreationally active males (V̇o2max: 49.5 ± 7.7 mL·kg-1·min-1) completed SL and DL cycling until Tlim within each intensity domain. Power output for SL trials was set at 60% of the corresponding DL trial. Before and immediately after Tlim, participants performed an isometric maximal voluntary contraction (MVC) coupled with one superimposed and three resting femoral nerve stimulations [100 Hz; 10 Hz; single twitch (Qtw)] to measure performance fatigability. Perceived fatigue, leg pain, dyspnea, and effort were collected during trials. Tlim within each intensity domain was not different between SL and DL (all P > 0.05). MVC declined more for SL versus DL following heavy- (-42 ± 16% vs. -30 ± 18%; P = 0.011) and severe-intensity cycling (-41 ± 12% vs. -31 ± 15%; P = 0.036). Similarly, peak Qtw force declined more for SL following heavy- (-31 ± 12% vs. -22 ± 10%; P = 0.007) and severe-intensity cycling (-49 ± 13% vs. -40 ± 7%; P = 0.048). Except for heavy intensity, voluntary activation reductions were similar between modes. Similarly, except for dyspnea, which was lower for SL versus DL across all domains, ratings of fatigue, pain, and effort were similar at Tlim between exercise modes. Thus, the amount of muscle mass modulates the extent of contractile function impairment in an intensity-dependent manner.NEW & NOTEWORTHY We investigated the modulatory role of muscle mass on performance and perceived fatigability across the entire intensity spectrum. Despite similar time-to-task failure, single-leg cycling resulted in greater impairments in muscle contractile function within the heavy- and severe-intensity domains, but not the moderate- and extreme-intensity domains. Perceived fatigue, pain, and effort were similar between cycling modes. This indicates that the modulatory role of muscle mass on the extent of performance fatigability is intensity domain-dependent.

The Quantification of Physical Performance and Internal Training Load in Youth Male Soccer Players During Preseason.

PURPOSE: The monitoring of training loads and quantification of physical performance are common practices in youth soccer academies to support coaches in prescribing and programming training for individuals. The interaction between training load and physical performance is unknown during a preseason period in youth soccer players. The current study assessed changes in training load and physical assessments across a 4-week preseason period. The relationship between physical performance and match playing time in youth male soccer players was also investigated. METHODS: The training loads of 25 professional youth academy male soccer players were monitored throughout a 4-week preseason period. Assessments of power, agility, speed, and aerobic capacity were undertaken in the first training session. Session ratings of perceived exertion (sRPE) and well-being questionnaires were collected during all training sessions and preseason matches. Playing time during subsequent competitive matches was recorded. RESULTS: T test and 30-m-sprint assessments, conducted on the first day of preseason, were predictors of sRPE throughout preseason (t test χ2/df = 2.895, poor adjustment; 30-m sprint χ2/df = 1.608, good adjustment). YoYo Test performance was related with changes in perceived fatigue (χ2/df = 0.534, very good adjustment). Faster players reported higher values of sRPE, and players with higher aerobic capacity reported higher levels of fatigue across preseason. Well-being, perceived fatigue and soreness, and sRPE decreased across preseason. Greater match durations were related to higher levels of fatigue during preseason (P < .05). CONCLUSION: The current study highlights the relationship between training load, physical assessments, and playing time. Coaches and practitioners can use physical test data at the start of preseason as an indication of players that report higher sRPE, perceived fatigue, and reduced well-being across preseason, supporting decisions around individualized training prescriptions.

Practices and perceptions of strength and conditioning training in female golf: A cross-sectional survey study of high-level amateur players.

This study aims to ascertain an in-depth understanding of current practices and perceptions of S&C training in high-level amateur female golfers. A cross-sectional, explorative survey study was constructed which asked questions relating to four key areas: i) general participant information, ii) current strength and conditioning (S&C) practices, iii) the perceived influence of S&C training on golf performance, and iv) knowledge and awareness of S&C. Results showed that the majority of female players had participated in some form of S&C training in the past, with the majority believing that clubhead speed and carry distance were the primary golfing metrics which could be positively impacted. More specifically, 91-97% of the players "Strongly agreed" or "Agreed" that the key physical characteristics for golf were strength and power for the lower and upper body, and flexibility. Interestingly, 58% of the players believed that S&C training should mimic the movement of the golf swing, which based off current evidence, is not how drive metrics and ultimately shots gained, can be maximised. This survey study provides useful information relating to the practices and perceptions of S&C training in high-level female amateur players and areas where education may be able to further advance player understanding of physical preparation.

Recovery following exercise-induced fatigue: Influence of a single heart rate clamped cycling session under systemic hypoxia.

We investigated whether a single heart rate clamped cycling session under systemic hypoxia affects the recovery of physical and psycho-physiological responses from residual fatigue compared to normoxia. On separate occasions, twelve trained males performed a 3-d acute training camp scenario. On days 1 and 3, participants cycled for 60 min at a constant heart rate (80% of ventilatory threshold). On day 2, fatigue was induced through a simulated team game circuit (STGC), followed by a 60-min intervention of either: (1) heart rate clamped cycling in normoxia; (2) heart rate clamped cycling in hypoxia (simulated altitude ~ 3500 m); or (3) no cycling. Countermovement jump height and leg stiffness were assessed before and after every session. Perceptual fatigue was evaluated daily. Compared to baseline, jump height decreased at all timepoints following the STGC (all p < 0.05). Leg stiffness and cycling power output only decreased immediately following the STGC, with a 48% further decrease in cycling power output in hypoxia compared to normoxia (p < 0.05). Perceived fatigue, decreased sleep quality, and increased muscle soreness responses occurred on day 3 (p < 0.05). A single heart rate-clamped cycling session in hypoxia reduced mechanical output without affecting recovery of physical performance and perceptual measures from residual fatigue induced through team sport activity.

Heart rate perception and expectation impact laboratory-induced perceived stress.

Previous studies have shown that the human capacity to gauge one's own physiological state is notoriously flawed. The cause for the mismatch between perceived and physiological stress has not yet been properly identified. In this study, we assumed that cardioceptive accuracy (CAc) is positively associated with cardiovascular reactivity, and CAc and expectation about stress might account for the discrepancy between perceived and physiological stress. In a crossover experiment, we assessed cardioceptive accuracy in two ways (mental heartbeat tracking task and perception of heart rate), and induced physiological (handgrip exercise) and mental (N-back task) stress in 64 university students (51 % male, mean age 22.2). We assessed cardiac and electrodermal activity, and expected and perceived stress. We found that indicators of cardioceptive accuracy were not associated with cardiovascular reactivity. However, heart rate perception moderated the association between the change in heart rate and perceived stress in the physical but not in the mental task. Whereas heartbeat tracking accuracy was not associated with perceived stress. Moreover, perceived stress was predicted by the expected stress but not by the change in heart rate and electrodermal activity in the mental stress task. In conclusion, heart rate perception and expectation of stress may shape perceived stress more than actual physiological changes in moderate acute stress.

Music Timing Differentiates Fatigue Perception and Performance during Isometric Strength Exercises: A Crossover Randomised Trial.

Music is well-known to elicit ergogenic effects on exercise performance; however, the moderating role of application timing remains unclear. This study examined the effects of the timing of music on fatigue perception and performance during isometric strength exercises. Using a within-subject, randomised crossover design, twelve recreationally active young adults performed two isometric strength tasks (plank-hold and wall-sit) in three separate conditions (MEE: music played during the entire exercise task; MDF: music played during fatigue alone; CON: no music). The total time to volitional exhaustion (TTE), time to the onset of fatigue perception (TFP), heart rate, and blood lactate responses were assessed during each trial. MEE resulted in a significantly longer TTE than CON in both the plank-hold (p < 0.05, d = 0.76) and wall-sit exercises (p < 0.05, d = 0.72), whereas MDF led to a significantly longer TTE than CON in wall-sit exercises alone (p < 0.05, d = 0.60). TFP was significantly longer in MEE than in CON in both the plank-hold (p < 0.05, d = 0.54) and wall-sit exercises (p < 0.05, d = 0.64). The music condition did not influence the heart rate or blood lactate changes in any of the trials. Our results suggest that listening to music during the entire exercise can delay the onset of fatigue perception in isometric strength tasks, whereas listening to music during fatigue has only a modest effect. Athletes and exercisers should consider extending music exposure throughout the entire exercise task to maximise performance benefits.

Physiological and perceptual responses to temperature step changes between cold and hot environments.

Objectives. This study explores the effects of temperature steps on thermal responses to understand abrupt temperature shifts faced by heat-exposed workers during winter. Methods. Three temperature step changes with three phases (S20: 20-40-20 °C, S30: 10-40-10 °C, S40: 0-40-0 °C) were conducted. Phase 1 took 30 min, phase 2 took 60 min and phase 3 took 40 min. Eleven participants remained sedentary throughout the experiment, and physiological responses, thermal perception and self-reported health symptoms were recorded. Results. In temperature up steps, steady skin temperature and sweating onset were delayed, and heart rate dropped by 10 bpm from S20 to S40. In temperature down steps to cold conditions, individuals transitioned from thermal comfort to discomfort and eventually cold strain. Blood pressure increased in temperature down steps, correlating with temperature step magnitudes. Thermal responses to temperature steps of equal magnitude but opposite directions were asymmetries, which weakened as step magnitude increased. Thermal perceptions responded faster than physiological changes after temperature steps, while self-reported health symptoms lagged behind physiological responses. Conclusions. These findings contribute to expanding basic data to understand the effects of temperature step magnitude and direction.

Contiguity in perception: origins in cellular associative computations.

Our brains are good at detecting and learning associative structures; according to some linguistic theories, this capacity even constitutes a prerequisite for the development of syntax and compositionality in language and verbalized thought. I will argue that the search for associative motifs in input patterns is an evolutionary old brain function that enables contiguity in sensory perception and orientation in time and space. It has its origins in an elementary material property of cells that is particularly evident at chemical synapses: input-assigned calcium influx that activates calcium sensor proteins involved in memory storage. This machinery for the detection and learning of associative motifs generates knowledge about input relationships and integrates this knowledge into existing networks through updates in connectivity patterns.

Effects of hazard type and confidence level on hazard perception in young male drivers: an ERP study.

Hazard perception refers to a driver's ability to identify potential hazards on the road. Although studies have shown that overconfidence affects drivers' ability to perceive hazards, the neural processing of hazard perception in overconfident drivers under different hazard types has rarely been investigated. A mixed experimental design of 2 (hazard type: hazards, no hazards) × 2 (driver group: overconfident driver, control group) was used. A total of 120 images (60 with hazards and 60 without hazards) were presented to 25 overconfident drivers and 25 drivers in the control group. Reaction time, response accuracy, P200 (200-250 ms), and N2 (280-330 ms) components were measured via event-related potential (ERP) technology. Response times of overconfident drivers are slower than those of the control group regardless of hazard types. The P200 latency of overconfident drivers was longer than that of their peers in hazard situations, while the P200 latency was similar between the two groups in no-hazard situations. Although a significant interaction was found on the N2 amplitude, no significant differences were found between the two groups in both hazard and no-hazard situations. Overconfident drivers have worse hazard perception performance in hazard situations with slower reaction times and greater P200 latencies than their peers. More importantly, P200 amplitude and N2 amplitude are sensitive to hazard types, while P200 amplitude and N2 latency can discriminate between driver groups. The findings help understand the negative impact of overconfidence on young drivers and contribute to the development and training of hazard perception tests.

The effects of sustained, low- and high-intensity isometric tasks on performance fatigability and the perceived responses that contributed to task termination.

PURPOSE: The present study examined the effects of sustained, isometric low- versus high-intensity tasks on time to task failure (TTF), performance fatigability (PF), ratings of perceived exertion (RPE), and the perceived causes of task termination from a post-test questionnaire (PTQ). METHODS: Ten men (mean ± SD: age = 21.1 ± 2.3 years; height = 180.2 ± 5.7 cm; body mass = 79.5 ± 8.8 kg) performed maximal voluntary isometric contractions (MVICs) before and after fatiguing, isometric forearm flexion tasks anchored to the torque corresponding to RPE values of 2 (TRQ2FT = 23.8 ± 7.1 N·m) and 8 (TRQ8FT = 60.9 ± 11.4 N·m). In addition, the subjects completed a PTQ which surveyed whether the perceived sensations of fatigue or pain, and/or the psychological factors of loss of focus and motivation contributed to the decision to terminate the task. Repeated measures ANOVAs, Wilcoxon-Signed Rank tests, and Spearman's Rank-Order Correlations were used to analyze the data. RESULTS: Across the fatiguing tasks, there were similar decreases in MVIC torque (95.2 ± 20.3 vs. 68.9 ± 15.6 N·m; p < 0.001) and RPE values (p = 0.122) at task failure for TRQ2FT (7.4 ± 2.7) and TRQ8FT (8.9 ± 1.0), but a longer (p = 0.005) TTF for the TRQ2FT (245.0 ± 177.0 s) than TRQ8FT (36.8 ± 11.1 s). CONCLUSIONS: Despite reaching task failure, the subjects were able to perform MVICs that were 100-300% greater than the target torque values within seconds of terminating the tasks. Thus, we hypothesized that task failure was not caused by an inability to produce sufficient torque to sustain the tasks, but rather an unwillingness to continue the task.

Influence of topical menthol gel on thermoregulation and perception while walking in the heat.

PURPOSE: Menthol is known to elicit opposing thermoregulatory and perceptual alterations during intense exercise. The current purpose was to determine the thermoregulatory and perceptual effects of topical menthol application prior to walking in the heat. METHODS: Twelve participants walked (1.6 m s-1, 5% grade) for 30 min in the heat (38 °C, 60% relative humidity) with either a 4% menthol or control gel on the upper (shoulder to wrist) and lower (mid-thigh to ankle) limbs. Skin blood flow (SkBF), sweat (rate, composition), skin conductivity, heart rate, temperature (skin, core), and thermal perception were measured prior to and during exercise. RESULTS: Skin conductivity expressed as time to 10, 20, 30, and 40 µS was delayed due to menthol (559 ± 251, 770 ± 292, 1109 ± 301, 1299 ± 335 s, respectively) compared to the control (515 ± 260, 735 ± 256, 935 ± 300, 1148 ± 298 s, respectively, p = 0.048). Sweat rate relative to body surface area was lower due to menthol (0.55 ± 0.16 L h-1 m(2)-1) than the control (0.64 ± 0.16 L h-1 m(2)-1, p = 0.049). Core temperature did not differ at baseline between the menthol (37.4 ± 0.3 °C) and control (37.3 ± 0.4 °C, p = 0.298) but was higher at 10, 20, and 30 min due to menthol (37.5 ± 0.3, 37.7 ± 0.2, 38.1 ± 0.3 °C, respectively) compared to the control (37.3 ± 0.4, 37.4 ± 0.3, 37.7 ± 0.3 °C, respectively, p < 0.05). The largest rise in core temperature from baseline was at 30 min during menthol (0.7 ± 0.3 °C) compared to the control (0.4 ± 0.2 °C, p = 0.004). Overall, the menthol treatment was perceived cooler, reaching "slightly warm" whereas the control treatment reached "warm" (p < 0.001). CONCLUSION: Menthol application to the limbs impairs whole-body thermoregulation while walking in the heat despite perceiving the environment as cooler.

Physiological and perceptual responses to acute arm cranking with blood flow restriction.

INTRODUCTION: Lower-body aerobic exercise with blood flow restriction (BFR) offers a unique approach for stimulating improvements in muscular function and aerobic capacity. While there are more than 40 reports documenting acute and chronic responses to lower-body aerobic exercise with BFR, responses to upper-body aerobic exercise with BFR are not clearly established. PURPOSE: We evaluated acute physiological and perceptual responses to arm cranking with and without BFR. METHODS: Participants (N = 10) completed 4 arm cranking (6 × 2 min exercise, 1 min recovery) conditions: low-intensity at 40%VO2peak (LI), low-intensity at 40%VO2peak with BFR at 50% of arterial occlusion pressure (BFR50), low-intensity at 40%VO2peak with BFR at 70% of arterial occlusion pressure (BFR70), and high-intensity at 80%VO2peak (HI) while tissue oxygenation, cardiorespiratory, and perceptual responses were assessed. RESULTS: During exercise, tissue saturation for BFR50 (54 ± 6%), BFR70 (55 ± 6%), and HI (54 ± 8%) decreased compared to LI (61 ± 5%, all P < 0.01) and changes in deoxyhemoglobin for BFR50 (11 ± 4), BFR70 (15 ± 6), and HI (16 ± 10) increased compared to LI (4 ± 2, all P < 0.01). During recovery intervals, tissue saturation for BFR50 and BFR70 decreased further and deoxyhemoglobin for BFR50 and BFR70 increased further (all P < 0.04). Heart rate for BFR70 and HI increased by 9 ± 9 and 50 ± 15b/min, respectively, compared to LI (both P < 0.02). BFR50 (8 ± 2, 1.0 ± 1.0) and BFR70 (10 ± 2, 2.1 ± 1.4) elicited greater arm-specific perceived exertion (6-20 scale) and pain (0-10 scale) compared to LI (7 ± 1, 0.2 ± 0.5, all P < 0.05) and pain for BFR70 did not differ from HI (1.7 ± 1.9). CONCLUSION: Arm cranking with BFR decreased tissue saturation and increased deoxyhemoglobin without causing excessive cardiorespiratory strain and pain.

The Relationship between Muscle Ultrasound Parameters and Diabetic Peripheral Neuropathy among Patients with Type 2 Diabetes Mellitus: A Cross-Sectional Study.

Background: Muscle dysfunction is an early complication of diabetic peripheral neuropathy (DPN). As a convenient and low-cost tool, muscle ultrasound has been used to assess muscle quality and muscle mass. However, the relationship between different muscle ultrasound parameters and DPN is unclear. Objectives: This study was designed to investigate the relationship between ultrasound parameters of different muscles and DPN among patients with type 2 diabetes mellitus, including the rectus femoris (RF), tibialis anterior (TA), and medial head of gastrocnemius (MG). Materials and Methods: The research enrolled 90 patients with type 2 diabetes mellitus (T2DM). All images were attained from both sides. Muscle measurements contained muscle thickness (MT), cross-sectional area (CSA), echo intensity (EI), and corrected EI. The binary logistic regression and multiple linear regression were used to investigate the association between muscle ultrasound parameters and DPN or vibration perception threshold (VPT). Results: EI, corrected EI, MT of MG, and EI of TA were associated with DPN separately after adjusting other clinical variates. Among these muscle parameters, the EI of MG had a better predictive value (OR: 1.114, 95% CI: 1.039, 1.196) of DPN. Combined with CSA of RF, peripheral artery disease (PAD), and sex, the corrected EI of MG was associated with the vibration perception threshold (VPT) (standard ß = 0.242, p < 0.001), better than the EI of MG (standard ß = 0.215, p = 0.002). Conclusions: MG (MT, EI, and corrected EI) and TA (EI) were associated with DPN, respectively. CSA of RF and corrected EI or EI of MG combined with PAD and sex were associated with VPT significantly, which supported that muscle ultrasound might be a substantial quantitative tool for detecting the exercise benefits for DPN.

Singing in different performance spaces: The effect of room acoustics on singers' perception.

Classical singers' performances vary across different acoustic environments. The changes in the delivery are influenced by the singer's perception of the venue's acoustics. This study investigated these relationships using nine professional or semi-professional classical singers. Participants performed Giordani's "Caro mio ben" aria in five venues, and the acoustic parameters reverberance (T30 and EDT), clarity (C80), early vocal support (STv), and tonal color (EDTf) were measured. From a factor analysis of the subjective analysis three major factors emerged that, we propose, would represent three generalized percepts of Room Supportiveness, Room Noiselessness, and Room Timbre. These percepts correlated significantly with objective acoustic parameters traditionally linked to vocal support, reverberation, and timbre. Room Supportiveness and Room Noiselessness significantly contributed to the singers' likability of the acoustic environment, while Room Timbre did not. This indicates that singers' perceptual preference for a performance space may be influenced by factors affecting both auditory feedback and vocal function. These findings underscore the need for performing space designers to consider the unique needs of all stakeholders, including listeners and performers. The study contributes to the bridging of the gap between subjective perceptions and objective measurements, providing valuable insights for acoustic design considerations.