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.

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.

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)

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.

Blood flow restricted walking alters gait kinematics.

This study investigated the impact of blood flow restriction (BFR) during treadmill walking on gait kinematics. Twenty-one participants completed one familiarisation and four experimental sessions, including two walking speeds (moderate [5.0 ± 0.3km·h-1] and fast [6.4 ± 0.4km·h-1]) and two occlusion conditions (BFR [60% of arterial occlusion pressure] and unrestricted). For each exercise intensity, the BFR session was performed first. Participants were instructed to walk as long as possible, with sessions capped at 20 min. Unrestricted sessions were time-matched, and the order of exercise intensity was randomised. Kinematics were collected over 10s every minute using retro-reflective markers affixed to specific body landmarks. Ratings of perceived exertion and discomfort were collected every two minutes. Blood samples were collected from the fingertip pre-exercise and the finger and toe post-exercise, and were analysed for lactate, electrolytes, and markers of cell-membrane damage. During the BFR sessions the cuffs remained inflated while the blood samples were collected. Fast-walk BFR sessions exhibited higher anterior trunk flexion (p = 0.001) and knee flexion during stance (p = 0.001) compared to all other sessions. Step width was increased during BFR sessions (p = 0.001), but no difference in step length (p = 0.300) or cadence (p = 0.922) were observed. The time required to elicit change in anterior trunk flexion and plantar-flexion angle at toe-off was shorter during BFR sessions (p = 0.024). The BFR sessions elicited the highest ratings of perceived exertion and discomfort, as well as blood lactate concentration (p ≤ 0.001). Application of BFR during moderate and fast treadmill walking modifies gait kinematics and exacerbates exercise-related sensations as well as blood lactate concentration.

Applying blood flow restriction changes walking kinematics, causing an overall increase in anterior trunk flexion and knee flexion during stance while simultaneously reducing plantar-flexion angle at toe-off and ankle joint velocity.Applying blood flow restriction exacerbate exercise-related sensations of exertion and discomfort.Sample site does not influence the level of post-exercise blood lactate or markers of cell-membrane potential and damage.

Exercise-induced responses in matrix metalloproteinases and osteopontin are not moderated by exercise format in males with overweight or obesity.

PURPOSE: Matrix metalloproteinase-2 (MMP-2) and -3 (MMP-3), and osteopontin (OPN) are associated with adipose-tissue expansion and development of metabolic disease. The purpose of the current study was to assess the circulating concentration of these markers, along with adiponectin and glucose concentrations, in response to acute exercise in individuals with overweight or obesity. METHODS: Fourteen sedentary males with overweight or obesity (29.0 ± 3.1 kg/m2) completed two separate, 3-day trials in randomised and counterbalanced order. An oral glucose tolerance test (OGTT) was performed on each day of the trial. Day two of each trial consisted of a single 30 min workload-matched bout of either high-intensity interval exercise (HIIE; alternating 100% and 50% of peak pulmonary oxygen uptake, [Formula: see text]O2peak) or continuous moderate intensity (CME; 60% [Formula: see text]O2peak) cycling completed 1 h prior to the OGTT. Glucose and physical activity were continuously monitored, while MMP-2, MMP-3, OPN and adiponectin were measured pre-, 0 h post-, 1 h post- and 25 h post-exercise. RESULTS: Exercise transiently increased MMP-3 and decreased OPN (both p < 0.01), but not MMP-2 or adiponectin. There were no differences in the response of inflammatory markers to the different exercise formats. Exercise increased mean daily glucose concentration and area under the glucose curve during the OGTT on Day 2 and Day 3 (main effect of time; p < 0.05). CONCLUSION: Acute cycling exercise decreased OPN, which is consistent with longer term improvements in cardiometabolic health and increased MMP-3, which is consistent with its role in tissue remodelling. Interestingly, exercise performed prior to the morning OGTT augmented the glucose concentrations in males. TRIAL REGISTRATION: ACTRN12613001086752.

Blood flow restriction during self-paced aerobic intervals reduces mechanical and cardiovascular demands without modifying neuromuscular fatigue.

This study examined cardiovascular, perceptual and neuromuscular fatigue characteristics during and after cycling intervals with and without blood flow restriction (BFR). Fourteen endurance cyclists/triathletes completed four 4-minute self-paced aerobic cycling intervals at the highest sustainable intensity, with and without intermittent BFR (60% of arterial occlusion pressure). Rest interval durations were six, four and four minutes, respectively. Power output, cardiovascular demands and ratings of perceived exertion (RPE) were averaged over each interval. Knee extension torque and vastus lateralis electromyography responses following electrical stimulation of the femoral nerve were recorded pre-exercise, post-interval one (+1, 2 and 4-minutes) and post-interval four (+1, 2, 4, 6 and 8-minutes). Power output during BFR intervals was lower than non-BFR (233 ± 54 vs 282 ± 60 W, p < 0.001). Oxygen uptake and heart rate during BFR intervals were lower compared to non-BFR (38.7 ± 4.5 vs 44.7 ± 6.44 mL kg-1 min-1, p < 0.001; 160 ± 14 vs 166 ± 10 bpm, p < 0.001), while RPE was not different between conditions. Compared to pre-exercise, maximal voluntary contraction torque and peak twitch torque were reduced after the first interval with further reductions following the fourth interval (p < 0.001) independent of condition (p = 0.992). Voluntary activation (twitch interpolation) did not change between timepoints (p = 0.375). Overall, intermittent BFR reduced the mechanical and cardiovascular demands of self-paced intervals without modifying RPE or knee-extensor neuromuscular characteristics. Therefore, BFR reduced the cardiovascular demands while maintaining the muscular demands associated with self-paced intervals. Self-paced BFR intervals could be used to prevent cardiovascular and perceptual demands being the limiting factor of exercise intensity, thus allowing greater physiological muscular demands compared to intervals without BFR.HighlightsThe use of blood flow restriction (BFR) during self-paced intervals (at the highest perceived sustainable intensity) causes a reduction in power output, pulmonary oxygen uptake and heart rate compared with non-restricted self-paced intervals.Despite lower mechanical and physiological demands during BFR cycling, the magnitude and aetiology of neuromuscular fatigue were not different to intervals without BFR, indicating the internal muscular load during BFR was elevated and potentially equivalent compared to without BFR.Self-paced intervals could be a suitable model to prescribe aerobic BFR exercise as an adjunct training stimulus for endurance cyclists.

Low- to moderate-intensity blood flow restricted walking is not an acute equivalent for unrestricted jogging in young active adults.

This study investigated whether walking with blood flow restriction (BFR) increases acute cardio-respiratory demands to the point that it can be considered an alternative for jogging. Sixteen physically active adults completed five experimental sessions (order randomised), comprising 10 min of treadmill exercise. Two sessions included unrestricted walking, two sessions required walking with BFR cuffs positioned on the lower limbs inflated to 60% of individualised arterial occlusion pressure, and one session was conducted at a jogging pace. Comfortable walking and jogging speeds were calculated during the familiarisation session. Walking speeds were individualised to either 100% (speed: 6.0 ± 0.3km·h-1[low-intensity]) or 120% (speed: 7.2 ± 0.3km·h-1[moderate-intensity]) of comfortable walking speed. The jogging session was unrestricted (speed: 9.1 ± 0.7km·h-1). Initial analysis compared walking conditions across heart rate, left cardiac work index, systolic blood pressure, relative oxygen consumption, minute ventilation, rating of perceived exertion and limb discomfort. Secondary analysis compared the walking session with the highest cardio-respiratory demands to jogging. Initial analysis identified that moderate-intensity with BFR induced the highest cardio-respiratory and perceptual responses compared with any other walking sessions (p < 0.01). Secondary analysis revealed that all cardio-respiratory measures were higher during jogging when compared with moderate-intensity with BFR (p < 0.01), except systolic blood pressure (p = 0.10). All perceptual measures were higher during moderate-intensity with BFR (p < 0.01) compared with jogging. Low- to moderate-intensity BFR-walking produces lower acute cardio-respiratory responses at higher ratings of perceived exertion and discomfort compared with jogging. Overall, BFR-walking does not seem to provide an equivalent exercise modality for unrestricted jogging in physically active adults.HighlightsIn young active adults, walking with blood flow restriction increases cardio-respiratory demands, yet not to a level equivalent to jogging.Moderate-intensity blood flow restricted walking elicits higher exercise-related sensation of exertion and leg discomfort than jogging.Blood flow restriction application increases exercise severity whereby moderate-intensity BFR-walking and jogging are both considered vigorous-intensity exercise.

Investigating the Link between Later-Life Brain Volume and Cardiorespiratory Fitness after Mild Traumatic Brain Injury Exposure.

INTRODUCTION: Evidence suggests that maintaining a higher level of cardiorespiratory fitness (CRF) later in life can offer some protection against brain volume loss as we age. By contrast, mild traumatic brain injury (mTBI) could accelerate age-related cortical atrophy. The current study sought to examine whether variations in the CRF level modified the association between mTBI history and brain volumetric measures in a sample of older adults. METHODS: Seventy-nine community-dwelling older adults (mean age 68.7 ± 4.3 years, 54.4% female) were assessed for their mTBI history: 25 participants (32%) reported sustaining at least one lifetime mTBI. Participants also underwent a CRF assessment and magnetic resonance imaging (MRI) to obtain global and region-of-interest volumes. RESULTS: Analysis of covariance, controlling for age, sex, education, and apolipoprotein (APOE) ε4 allele carriage, revealed that participants with a history of mTBI had a significantly larger total mean grey matter volume (582.21 ± 12.46 cm3) in comparison to participants with no mTBI history (571.08 ± 17.21 cm3, p = 0.01 after correction for multiple comparisons). However, no differences between groups based on mTBI history were found for total white matter volume or in any other cortical or subcortical structures examined. A subsequent moderation analysis found that CRF was predominantly non-influential on the association between mTBI history and the MRI-quantified measures of brain volume. CONCLUSION: While unexpected, the findings suggest that a history of mTBI can lead to grey matter alterations in the ageing brain. However, concurrent variations in the CRF level did not influence the differences in brain volume found based on mTBI exposure status.