Exploration of Alzheimer's disease-related gene expression following high-intensity and moderate-intensity exercise interventions.

OBJECTIVES: There are currently 29 genome regions that demonstrate associations with Alzheimer's disease (AD) risk. Regular physical exercise can promote systemic change in gene expression and may modify the risk of cognitive decline and AD. This study is a secondary analysis of a randomised controlled trial and examines the effect of a six-month exercise intervention versus control on AD-related gene expression. DESIGN: Single-site parallel pilot randomised controlled trial. METHODS: 91 cognitively unimpaired older adults were enrolled in the Intense Physical Activity and Cognition (IPAC) study. Participants were randomised into one of three groups: high-intensity exercise, moderate-intensity exercise, or inactive control for six months. Blood samples were collected prior to, and within two weeks of intervention completion, for later expression analysis of 96 genes. To explore the relationship between changes in gene expression and the intervention groups, an interaction term ("time point × intervention group") was subsequently used. RESULTS: There were no significant differences in gene expression between the three intervention groups at baseline, nor after the intervention. Within groups, five genes were upregulated, seven were downregulated and the remainder remained unchanged. None of the examined genes showed significant change from pre- to post-intervention in the exercise groups compared to the control. CONCLUSIONS: Exercise does not change AD-related gene expression in cognitively unimpaired older adults. Several gene expression targets have been identified for further study.

Estimating cardiorespiratory fitness in older adults using the international physical activity questionnaire.

Introduction: Non-exercise estimates of cardiorespiratory fitness hold great utility for epidemiological research and clinical practice. Older adults may yield the greatest benefit from fitness estimates due to limited capacity to undergo strenuous maximal exercise testing, however, few of the previously developed non-exercise equations are suitable for use in older adults. Thus, the current study developed a non-exercise equation for estimating cardiorespiratory fitness in older adults derived from the widely used International Physical Activity Questionnaire (IPAQ). Methods: This study was a secondary analysis of baseline data from a randomized controlled trial. Participants were community-dwelling, cognitively unimpaired older adults aged 60-80 years (n = 92). They completed the IPAQ and underwent maximal exercise testing on a cycle ergometer. Stepwise linear regression was used to determine the equation in a randomly selected, sex-balanced, derivation subset of participants (n = 60), and subsequently validated using a second subset of participants (n = 32). Results: The final equation included age, sex, body mass index and leisure time activity from the IPAQ and explained 61% and 55% of the variance in the derivation and validation groups, respectively (standard error of estimates = 3.9, 4.0). Seventy-seven and 81% of the sample fell within ±1SD (5.96 and 6.28 ml·kg-1·min-1) of measured VO2peak for the derivation and validation subgroups. The current equation showed better performance compared to equations from Wier et al. (2006), Jackson et al. (1990), and Schembre & Riebe (2011), although it is acknowledged previous equations were developed for different populations. Conclusions: Using non-exercise, easily accessible measures can yield acceptable estimates of cardiorespiratory fitness in older adults, which should be further validated in other samples and examined in relation to public health outcomes.

Contribution of Physical Characteristics to Game Performance in Male Wheelchair Basketball Athletes at the Tokyo Paralympic Games.

ABSTRACT: Snyder, L, Goods, PSR, Peeling, P, Balloch, A, Peiffer, JJ, Binnie, MJ, and Scott, BR. Contribution of physical characteristics to game performance in male wheelchair basketball athletes at the Tokyo Paralympic Games. J Strength Cond Res XX(X): 000-000, 2024-This investigation explored the physical characteristics of elite male wheelchair basketball (WCB) athletes and their association with game performance during the Tokyo 2020 Paralympic Games. Sixteen male athletes from the Australian national WCB squad were assessed for anthropometrics, speed, change of direction, aerobic power, and upper-body power during a training camp before the 2020 Paralympic Games. Athletes were grouped according to the International Wheelchair Basketball Federation disability classification system (1.0-4.5) as low- (≤2.5, more severe impairments) or high-point (≥3.0, less severe impairments) athletes. Physical and performance characteristics between groups were compared using independent-samples t-tests, and their relationship to game statistics (points, rebounds, assists, and steals) per minute played was explored through stepwise regression. High-point athletes were 13% taller (p = 0.001), 4-9% faster (p < 0.001-0.017), and demonstrated superior change of direction ability (15%, p < 0.001) compared with low-point athletes. Approximately 74% of the variance in points scored per minute was accounted for by athlete classification, whereas the most important modifiable physical characteristic was speed, which contributed significantly to steals (54% of variance) and assists (96% of variance when arm span and sitting reach height were also considered). Low-point athletes with spinal cord injuries generally have impaired trunk control, which is a likely explanation for performance differences between groups. A range of nonmodifiable (classification, sitting reach height, and arm span) and modifiable (speed) physical characteristics contribute to game performance outcomes and should therefore be considered when identifying, developing, and selecting WCB athletes for elite competition.

Continuous blood flow restriction during repeated-sprint exercise increases peripheral but not systemic physiological and perceptual demands.

This study examined the impact of continuous blood flow restriction (BFR) during repeated-sprint exercise (RSE) on acute performance, peripheral, systemic physiological, and perceptual responses. In a randomized crossover design, 26 adult male semi-professional and amateur team-sport players completed two RSE sessions (3 sets of 5 × 5-s sprints with 25 s of passive recovery and 3 min of rest) with continuous BFR (45% arterial occlusion; excluding during between-set rest periods) or without (non-BFR). Mean and peak power output were significantly lower (p < 0.001) during BFR compared to non-BFR (dz = 0.85 and 0.77, respectively). Minimum tissue saturation index during the sprints and rest periods was significantly reduced (p < 0.001) for BFR (dz = 1.26 and 1.21, respectively). Electromyography root mean square was significantly decreased (p < 0.01) for biceps femoris and lateral gastrocnemius muscles during BFR (dz = 0.35 and 0.79, respectively), but remained unchanged for the vastus lateralis muscle in both conditions. Oxygen consumption and minute ventilation were significantly reduced (both p < 0.01) for BFR (dz = 1.46 and 0.43, respectively). Perceived limb discomfort was significantly higher (p < 0.001) for BFR (dz = 0.78). No differences (p > 0.05) in blood lactate concentration or rating of perceived exertion were observed between conditions. Blood flow-restricted RSE reduced performance and likely increased the physiological and perceptual stimulus for the periphery with greater reliance on anaerobic glycolysis, despite comparable or decreased systemic demands.

Automatic adjustment of cycle ergometer power output to accurately clamp heart rate.

We assessed the accuracy and inter-sessional reliability of traditional (manual) compared to automatic (AutoHR) heart rate (HR) clamping methods during submaximal intensity continuous cycling. On separate occasions, thirteen males cycled at an HR corresponding to 80% of the ventilatory threshold for 18 min. Cycling power output was adjusted using either manual or AutoHR methods, encompassing three trials per method. For the manual method, cycling power output was adjusted every 30 s by 0, 5 or 10 W at the experimenter's discretion. Conversely, AutoHR automatically adjusted power output based on the difference between target and actual HR. Participants' HR was measured at 1 Hz. Root-mean square error (RMSE) and intraclass correlation coefficients (ICC) were calculated from the difference between measured and target HR to represent accuracy and reliability of each method. The RMSE for the manual method (3.2 ± 2.6 bpm) was significantly higher compared to AutoHR (2.8 ± 2.3 bpm) (p < 0.01, r = 0.13); inter-day ICC were 0.92 and 0.89 for manual adjustment and AutoHR, respectively. Automatic methods to clamp HR are more accurate than manual approaches during submaximal intensity continuous cycling and can be easily implemented for uniform HR control in individual and group training sessions at minimal cost.

Can period-related symptoms predict menstrual manipulation among Australian female cyclists?

This study explored the extent of menstrual manipulation and its associated impact on period-related symptoms and training disruptions in Australian Female Cyclists. 205 female cyclists, from recreational to elite level, participated in an online "Female Cyclist Questionnaire (FCQ)". The FCQ utilised a series of validated questionnaires to obtain demographic information and menstrual function of the respondents, and to investigate their menstrual manipulation habits and perceptions on how their period-related symptoms affected their well-being, mood, energy and training tolerance. More than 80% of the cyclists reported that their period-related symptoms impacted upon training and 41% made training adjustments based on these symptoms. Two-thirds of respondents thought their training should be phase-controlled yet only half discussed their hormonal cycles with their coaches. Menstrual manipulation was predicted by reduced "workout tolerance" in these cyclists (odds ratio = 0.632). Half of the respondents reported compromised ability to tolerate high-intensity interval training with period-related symptoms. Period pain, increased irritability, lower energy levels and more sugar cravings were commonly reported but did not predict menstrual manipulation. The data indicated that period-related symptoms are present in Australian female cyclists across all levels of participation. However, the perceived impact to training and subsequent behavioural changes varied among individuals.

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.

Dose-response effects of exercise on mental health in community-dwelling older adults: Exploration of genetic moderators / Efectos dosis-respuesta del ejercicio sobre la salud mental en adultos mayores que viven en la comunidad: exploración de moderadores genéticos

Background/Objective: (1) Examine the role of exercise intensity on mental health symptoms in a community-based sample of older adults. (2) Explore the moderating role of genetic variation in brain-derived neurotrophic factor (BDNF) and apolipoprotein E (APOE) on the effects of exercise on mental health symptoms. Method: This study is a secondary analysis of a three-arm randomized controlled trial, comparing the effects of 6 months of high-intensity aerobic training vs. moderate-intensity aerobic training vs. a no-contact control group on mental health symptoms assessed using the Depression, Anxiety, and Stress Scale (DASS). The BDNF Val66Met polymorphism and APOE ε4 carrier status were explored as genetic moderators of exercise effects on mental health symptoms. Results: The exercise intervention did not influence mental health symptoms. The BDNF Val66Met polymorphism did not moderate intervention effects on mental health symptoms. APOE ε4 carrier status moderated the effect of intervention group on perceived stress over 6 months, such that APOE ε4 carriers, but not non-carriers, in the high-intensity aerobic training group showed a decline in perceived stress over 6 months. Conclusions: APOE ε4 carrier status may modify the benefits of high-intensity exercise on perceived stress such that APOE ε4 carriers show a greater decline in stress as a result of exercise relative to non-APOE ε4 carriers.(AU)

The impact of exercise on blood-based biomarkers of Alzheimer's disease in cognitively unimpaired older adults.

Physical activity is a promising preventative strategy for Alzheimer's disease: it is associated with lower dementia risk, better cognition, greater brain volume and lower brain beta-amyloid. Blood-based biomarkers have emerged as a low-cost, non-invasive strategy for detecting preclinical Alzheimer's disease, however, there is limited literature examining the effect of exercise (a structured form of physical activity) on blood-based biomarkers. The current study investigated the influence of a 6-month exercise intervention on levels of plasma beta-amyloid (Aß42, Aß40, Aß42/40), phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) chain in cognitively unimpaired older adults, and as a secondary aim, whether blood-based biomarkers related to cognition. Ninety-nine community-dwelling older adults (69.1 ± 5.2) were allocated to an inactive control, or to moderate or high intensity exercise groups where they cycled twice weekly for six months. At baseline and six months (post-intervention), fasted blood was collected and analysed using single molecule array (SIMOA) assays, and cognition was assessed. Results demonstrated no change in levels of any plasma biomarker from pre- to post-intervention. At baseline, higher NfL was associated with poorer cognition (ß = -0.33, SE = 0.13, adjusted p = .042). Exploratory analyses indicated higher cardiorespiratory fitness was associated with higher NfL and GFAP levels in apolipoprotein E (APOE) ε4 non-carriers compared to ε4 carriers (NfL, ß = -0.43, SE = 0.19, p = .029; GFAP, ß = -0.41, SE = 0.20, p = .044), though this association was mediated by body mass index (BMI). These results highlight the importance of considering BMI in analysis of blood-based biomarkers, especially when investigating differences between APOE ε4 carriers and non-carriers. Our results also indicate that longer follow-up periods may be required to observe exercise-induced change in blood-based biomarkers.

Single- Versus Double-Leg Cycling: Small Muscle Mass Exercise Improves Exercise Capacity to a Greater Extent in Older Compared With Younger Population.

Manipulating the amount of muscle mass engaged during exercise can noninvasively inform the contribution of central cardiovascular and peripheral vascular-oxidative functions to endurance performance. To better understand the factors contributing to exercise limitation in older and younger individuals, exercise performance was assessed during single-leg and double-leg cycling. 16 older (67 ± 5 years) and 14 younger (35 ± 5 years) individuals performed a maximal exercise using single-leg and double-leg cycling. The ratio of single-leg to double-leg cycling power (RatioPower SL/DL) was compared between age groups. The association between fitness (peak oxygen consumption, peak power output, and physical activity levels) and RatioPower SL/DL was explored. The RatioPower SL/DL was greater in older compared with younger individuals (1.14 ± 0.11 vs. 1.06 ± 0.08, p = .041). The RatioPower SL/DL was correlated with peak oxygen consumption (r = .886, p < .001), peak power output relative to body mass (r = .854, p < .001), and levels of physical activity (r = .728, p = .003) in the younger but not older subgroup. Reducing the amount of muscle mass engaged during exercise improved exercise capacity to a greater extent in older versus younger population and may reflect a greater reduction in central cardiovascular function compared with peripheral vascular-oxidative function with aging.

Dose-response effects of exercise on mental health in community-dwelling older adults: Exploration of genetic moderators.

Background/Objective: (1) Examine the role of exercise intensity on mental health symptoms in a community-based sample of older adults. (2) Explore the moderating role of genetic variation in brain-derived neurotrophic factor (BDNF) and apolipoprotein E (APOE) on the effects of exercise on mental health symptoms. Method: This study is a secondary analysis of a three-arm randomized controlled trial, comparing the effects of 6 months of high-intensity aerobic training vs. moderate-intensity aerobic training vs. a no-contact control group on mental health symptoms assessed using the Depression, Anxiety, and Stress Scale (DASS). The BDNF Val66Met polymorphism and APOE ε4 carrier status were explored as genetic moderators of exercise effects on mental health symptoms. Results: The exercise intervention did not influence mental health symptoms. The BDNF Val66Met polymorphism did not moderate intervention effects on mental health symptoms. APOE ε4 carrier status moderated the effect of intervention group on perceived stress over 6 months, such that APOE ε4 carriers, but not non-carriers, in the high-intensity aerobic training group showed a decline in perceived stress over 6 months. Conclusions: APOE ε4 carrier status may modify the benefits of high-intensity exercise on perceived stress such that APOE ε4 carriers show a greater decline in stress as a result of exercise relative to non-APOE ε4 carriers.

Effects of In-Exercise Carbohydrate Supplementation on Prolonged High-Intensity Exercise Performance in Oral Contraceptive Users.

PURPOSE: To examine the impact of oral contraceptive (OC) phases on performance, physiological, and subjective responses to prolonged, intensive exercise when carbohydrate (CHO) stores are reduced. METHODS: Ten well-trained female cyclists using monophasic OC completed 4 identical trials (>150 min) under conditions of in-trial 60-g·h-1 CHO supplementation (CHO+) or placebo (CHO-) during the sugar- (SUG) and active-pill (ACT) phases of their OC cycle. Each trial comprised two 400-kcal time trials (TT) separated by 1 hour of submaximal cycling at first ventilatory threshold. RESULTS: Change in completion time from TT1 to TT2 was minimized in CHO+ compared with CHO- (4.06 [2.55] vs 6.08 [5.33] min; P = .019, effect size = -0.36). An interaction effect of OC and CHO was observed for time to complete TT (P = .006), mean TT power (P = .002), mean TT heart rate (P = .002), and posttrial emotional balance (P = .020) and negative emotional state (P = .033). In ACT, mean TT power and heart rate were higher in CHO+ when compared with CHO-, resulting in faster TTs in CHO+ and improved posttrial emotional well-being. When CHO was not supplemented, TT power and heart rate were higher in SUG when compared with ACT, resulting in faster TTs in SUG and improved posttrial emotional balance. CONCLUSION: CHO depletion during ACT negatively influenced TT performance and emotional well-being when compared with SUG. Irrespective of OC pill phase, CHO supplementation should be prioritized to sustain performance and improve postexercise recovery-stress balance.

Fatigue Resistance Is Altered during the High-Hormone Phase of Eumenorrheic Females but Not Oral Contraceptive Users.

PURPOSE: This study aimed to examine the effect of ovarian hormones and their synthetic equivalents on substrate utilization and fatigue resistance during a race-specific cycling protocol. METHODS: Seventeen well-trained female cyclists (nine eumenorrheic females, eight oral contraceptive users) completed two experimental trials, in a randomized order, in their low- (follicular/sugar pill) and high-hormone (luteal/active pill) phases. Each 91-min trial consisted of a 45-min moderate-intensity component (submaximal cycling, or SMC) followed by 6 min of high-intensity (HIT) and then a fatigue resistance test (FRT): 6 × 1-min all-out efforts with 1-min active recovery. Meals, comprising carbohydrate (CHO) intake of 8 g·kg -1 body mass, were standardized 24-h pretrial. An electrolyte-only solution was provided ad libitum during each trial. RESULTS: In eumenorrheic females, a large reduction in average power during FRT was observed in the luteal phase (277 ± 31 vs 287 ± 33 W; P = 0.032). Greater CHO ox (~ 4%, P = 0.020) during SMC and ventilatory inefficiencies during SMC and HIT (~7%, P < 0.001) were also observed in the luteal phase. In contraceptive users, despite some phasal changes in cardiorespiratory and metabolic data in SMC (~6% higher blood glucose and ~2% higher minute ventilation in active pill phase), none of the performance parameters in the FRT were different. CONCLUSIONS: Fatigue resistance was compromised only in high-hormone phase of the menstrual cycle, with eumenorrheic females likely susceptible because of increased CHO utilization during SMC. Hormone-induced ventilatory inefficiencies may also have increased metabolic demand. These findings emphasize the need to maintain CHO availability for power production, particularly in high-hormone phases.

Repeated-Sprint Training With Blood-Flow Restriction Improves Repeated-Sprint Ability Similarly to Unrestricted Training at Reduced External Loads.

PURPOSE: This study examined performance and physiological adaptations following 3 weeks of repeated-sprint training (RST) with blood-flow restriction (BFR) or without (non-BFR). METHODS: Twenty-six semiprofessional and amateur adult male team-sport players were assessed for repeated-sprint ability, anaerobic capacity, leg lean mass, neuromuscular function, and maximal aerobic capacity before and after RST. Participants completed 9 cycling RST sessions (3 sets of 5-7 × 5-s sprints, 25-s passive recovery, 3-min rest) over a 3-week period with BFR or non-BFR. RESULTS: During RST sessions, the BFR group demonstrated lower mean power output compared with non-BFR (-14.5%; g = 1.48; P = .001). Significant improvements (P < .05) in mean and peak power output during repeated-sprint ability (+4.1%; g = 0.42, and + 2.2%; g = 0.25, respectively) and anaerobic capacity (+4.8%; g = 0.47, and + 4.7%; g = 0.32, respectively) tests, leg lean mass (+2.0%; g = 0.16), and peak aerobic power (+3.3%; g = 0.25) were observed from pretesting to posttesting without any between-groups differences. No significant changes (P > .05) were observed for maximal isometric voluntary contraction and maximal aerobic capacity. Peak rate of force development decreased (P = .003) in both groups following RST (-14.6%; g = 0.65), without any between-groups differences. CONCLUSIONS: Repeated-sprint ability, anaerobic capacity, leg lean mass, and peak aerobic power improved following 3 weeks of RST; however, the addition of BFR did not further enhance adaptations. Interestingly, comparable improvements were achieved between groups despite lower external loads experienced during RST sessions with BFR.

Manipulating Internal and External Loads During Repeated Cycling Sprints: A Comparison of Continuous and Intermittent Blood Flow Restriction.

ABSTRACT: Mckee, JR, Girard, O, Peiffer, JJ, and Scott, BR. Manipulating internal and external loads during repeated cycling sprints: A comparison of continuous and intermittent blood flow restriction. J Strength Cond Res 38(1): 47-54, 2024-This study examined the impact of blood flow restriction (BFR) application method (continuous vs. intermittent) during repeated-sprint exercise (RSE) on performance, physiological, and perceptual responses. Twelve adult male semi-professional Australian football players completed 4 RSE sessions (3 × [5 × 5-second maximal sprints:25-second passive recovery], 3-minute rest between the sets) with BFR applied continuously (C-BFR; excluding interset rest periods), intermittently during only sprints (I-BFR WORK ), or intraset rest periods (I-BFR REST ) or not at all (Non-BFR). An alpha level of p < 0.05 was used to determine significance. Mean power output was greater for Non-BFR ( p < 0.001, dz = 1.58 ), I-BFR WORK ( p = 0.002, dz = 0.63 ), and I-BFR REST ( p = 0.003, dz = 0.69 ) than for C-BFR and for Non-BFR ( p = 0.043, dz = 0.55 ) compared with I-BFR REST . Blood lactate concentration ( p = 0.166) did not differ between the conditions. Mean oxygen consumption was higher during Non-BFR ( p < 0.001, dz = 1.29 and 2.31; respectively) and I-BFR WORK ( p < 0.001, dz = 0.74 and 1.63; respectively) than during I-BFR REST and C-BFR and for I-BFR REST ( p = 0.002, dz = 0.57) compared with C-BFR. Ratings of perceived exertion were greater for I-BFR REST ( p = 0.042, dz = 0.51) and C-BFR ( p = 0.011, dz = 0.90) than for Non-BFR and during C-BFR ( p = 0.023, dz = 0.54) compared with I-BFR WORK . Applying C-BFR or I-BFR REST reduced mechanical output and cardiorespiratory demands of RSE and were perceived as more difficult. Practitioners should be aware that BFR application method influences internal and external demands during RSE.

Maintenance of internal load despite a stepwise reduction in external load during moderate intensity heart rate clamped cycling with acute graded normobaric hypoxia in males.

OBJECTIVES: To investigate the acute effects of graded hypoxia on external and internal loads during 60 min of endurance cycling at a clamped heart rate. DESIGN: Repeated measures. METHODS: On separate visits, 16 trained males cycled for 60 min at a clamped heart rate corresponding to 80 % of their first ventilatory threshold at sea-level and 2500 m, 3000 m, 3500 m and 4000 m simulated altitudes (inspired oxygen fractions of 20.9 %, 15.4 %, 14.5 %, 13.6 % and 12.7 %, respectively). Markers of external (power output) and internal (blood lactate concentration, tissue saturation index, cardio-respiratory and perceptual responses) loads were measured every 15 min during cycling. Neuromuscular function of knee extensors was characterised pre- and post-exercise. RESULTS: Compared to sea-level (101 ±â€¯22 W), there was a stepwise reduction in power output with increasing hypoxia severity (-17.9 ±â€¯8.9 %, -27.1 ±â€¯10.7 %, -34.2 ±â€¯12.0 % and - 44.6 ±â€¯15.1 % at 2500 m, 3000 m, 3500 m, and 4000 m, respectively, all p < 0.05). Blood lactate and tissue saturation index were not different across hypoxia severities, and perceptual responses were exacerbated at 4000 m only, with increased breathing difficulty. Knee extensor torque decreased post-exercise (-14.5 ±â€¯9.0 %, p < 0.05), independent of condition. CONCLUSIONS: Increasing hypoxia severity reduces cycling power output and arterial oxygen saturation in a stepwise fashion without affecting exercise responses between sea-level and simulated altitudes up to 3500 m despite breathing difficulty being elevated at 4000 m.

The intensity of a resistance exercise session can be quantified by the work rate of exercise.

PURPOSE: Athletes regularly perform resistance training, yet it is unknown how best to monitor its intensity. This study compared different resistance exercise intensity metrics to determine their sensitivity to manipulating work rate (via altering inter-set rest and load). METHODS: Following baseline testing for 10- and 3-repetition maximum (RM; squat and bench press), fourteen trained participants completed four volume-matched protocols in a randomised order: 3x10 with 85% 10RM, 60 s rest (3x1060s); 3x10 with 85% 10RM, 180 s (3x10180s); 8x3 with 85% 3RM, 120 s (8x3120s); 8x3 with 85% 3RM, 300 s (8x3300s). Internal intensity was quantified via rate of oxygen consumption ([Formula: see text]), heart rate, blood lactate concentration, and rating of perceived exertion (RPE). External intensity was assessed via previously developed "Training-Intensity" (TI) and "Intensity-Index" (II) metrics, and from exercise work rate (expressed as kg∙min-1 and joules∙min-1). RESULTS: Internal intensity and work-rate metrics were highest for 3x1060s, followed by 3x10180s, 8x3120s and 8x3300s (p≤0.027). TI and II were higher for 8x3 than 3x10 protocols (p<0.001), but not different within these configurations. Internal intensity measures were more strongly correlated with work rate (r = 0.37-0.96) than TI and II (r = -0.42-0.33) metrics. CONCLUSIONS: Work rate corroborated objective internal intensity metrics during resistance exercise, with the highest work rate session (3x1060s) also eliciting greater RPE scores than other protocols. In contrast, the TI and II did not agree with other intensity measures, likely because they do not consider rest periods. Practitioners can plan for the physiological and perceptual demands of resistance training by estimating work rate.

The velocity of resistance exercise does not accurately assess repetitions-in-reserve.

This study assessed the reliability of mean concentric bar velocity from 3- to 0-repetitions in reserve (RIR) across four sets in different exercises (bench press and prone row) and with different loads (60 and 80% 1-repetition maximum; 1RM). Whether velocity values from set one could be used to predict RIR in subsequent sets was also examined. Twenty recreationally active males performed baseline 1RM testing before two randomised sessions of four sets to failure with 60 or 80% 1RM. A linear position transducer measured mean concentric velocity of repetitions, and the velocity associated with each RIR value up to 0-RIR. For both exercises, velocity decreased between each repetition from 3- to 0-RIR (p ≤ 0.010). Mean concentric velocity of RIR values was not reliable across sets in the bench press (mean intraclass correlation coefficient [ICC] = 0.40, mean coefficient of variation [CV] = 21.3%), despite no significant between-set differences (p = 0.530). Better reliability was noted in the prone row (mean ICC = 0.80, mean CV = 6.1%), but velocity declined by 0.019-0.027 m·s-1 (p = 0.032) between sets. Mean concentric velocity was 0.050-0.058 m·s-1 faster in both exercises with 60% than 80% 1RM with (p < 0.001). At the individual level, the velocity of specific RIR values from set one accurately predicted RIR from 5- to 0-RIR for 30.9% of repetitions in subsequent sets. These findings suggest that velocity of specific RIR values vary across exercises, loads and sets. As velocity-based RIR estimates were not accurate for 69.1% of repetitions, alternative methods to should be considered for autoregulating of resistance exercise in recreationally active individuals.

Bar velocity of bench press and prone row repetitions decreases on average from 3- to 0-repetitions in reserve (RIR) and is faster for lighter versus heavier loadsThe velocity of 3- to 0-RIR varied across four sets for the prone row but was more reliable for the prone row than the bench pressAt the individual participant level, there was not a consistent decrease in velocity between consecutive repetitions, and target velocities for specific RIR values were not correctly predicted in most cases.Using velocity stops may not be an appropriate method to predict specific RIR in recreationally active individuals.

Blood-Flow Restriction Is Associated With More Even Pacing During High-Intensity Cycling.

PURPOSE: This study examined the influence of blood-flow restriction (BFR) on the distribution of pace, physiological demands, and perceptual responses during self-paced cycling. METHODS: On separate days, 12 endurance cyclists/triathletes were instructed to produce the greatest average power output during 8-minute self-paced cycling trials with BFR (60% arterial occlusion pressure) or without restriction (CON). Power output and cardiorespiratory variables were measured continuously. Perceived exertion, muscular discomfort, and cuff pain were recorded every 2 minutes. RESULTS: Linear regression analysis of the power output slope was statistically significant (ie, deviated from the intercept) for CON (2.7 [3.2] W·30 s-1; P = .009) but not for BFR (-0.1 [3.1] W·30 s-1; P = .952). Absolute power output was ∼24% (12%) lower at all time points (P < .001) during BFR compared with CON. Oxygen consumption (18% [12%]; P < .001), heart rate (7% [9%]; P < .001), and perceived exertion (8% [21%]; P = .008) were reduced during BFR compared with CON, whereas muscular discomfort (25% [35%]; P = .003) was greater. Cuff pain was rated as "strong" (5.3 [1.8] au; 0-10 scale) for BFR. CONCLUSION: Trained cyclists adopted a more even distribution of pace when BFR was applied compared with a negative distribution during CON. By presenting a unique combination of physiological and perceptual responses, BFR is a useful tool to understand how the distribution of pace is self-regulated.