An unusual case of marathon-related exercise associated collapse: Case report and some considerations for medical care at endurance mass participation events.

This article presents a unique exercise-associated collapse case during a marathon, highlighting the significance of evidence-based management for athletes on field. The patient, a 61-year-old experienced runner, collapsed near the finish line of the Milano City Marathon. He was aided immediately with CPR and AED. After excluding, through validated algorithms, common and life-threatening causes of collapse, the patient was transferred to hospital. The patient underwent diagnostic procedures, including CT and MRI scans, and hormonal tests that revealed pituitary hemorrhage and underlying coronary artery disease. Follow-up assessments and personalized care were instrumental in the patient's successful recovery and safe return to exercise.

Exertional Rhabdomyolysis in Athletes: Systematic Review and Current Perspectives.

OBJECTIVE: Exertional rhabdomyolysis results from a breakdown of skeletal muscle cells after intense exercise in otherwise healthy patients, causing increased levels of creatine kinase (CK) or myoglobin, as well as urine dipstick positive for blood, and may result in kidney insufficiency. The aim of this study was to outline the current perspectives of exertional rhabdomyolysis in athletes and subsequent treatment based on the current literature. DATA SOURCES: We searched the MEDLINE/PubMed and Google databases for ([exercise] OR [exertional]) AND rhabdomyolysis following the PRISMA guidelines. All abstracts were reviewed by 2 independent examiners. Inclusion criteria consisted of original articles presenting studies on exertional rhabdomyolysis or exercise-induced rhabdomyolysis with 7 or more cases. All case reports, case series, or editorials were excluded. MAIN RESULTS: A total of 1541-abstracts were screened, leaving 25 studies for final inclusion and analysing 772patients. Especially, young male patients were affected at a mean age of 28.7 years (range 15.8-46.6 years). Most of the athletes performed running, including marathons in 54.3% of cases (n = 419/772), followed by weightlifting in 14.8% (n = 114/772). At the time of presentation, the mean creatine kinase was 31 481 IU/L (range 164-106,488 IU/L). Seventeen studies reported the highest level of CK, which was 38 552 IU/L (range 450-88,496 IU/L). For treatment, hydration was the most common method of choice reported by 8 studies. CONCLUSIONS: Exertional rhabdomyolysis seems to be underestimated, and it is essential to screen patients who present with muscle soreness/cramps and/or dark urine after heavy endurance events to avoid any further complications. LEVEL OF EVIDENCE: II; systematic review.

Effects of far-infrared radiation lamp therapy on recovery from muscle damage induced by eccentric exercise.

The present study investigated the effects of a far-infrared radiation (FIR) lamp therapy on changes in muscle damage and proprioception markers after maximal eccentric exercise of the elbow flexors (EF: Study 1) and the knee flexors (KF: Study 2) in comparison to a sham treatment condition. In each study, 24 healthy sedentary women were assigned to a FIR or a sham treatment group (n = 12/group). They performed 72 maximal EF eccentric contractions (Study 1) or 100 maximal KF eccentric contractions (Study 2) with their non-dominant limbs. They received a 30-min FIR (wavelength: 8-14 µm) or sham treatment at 1, 25, 49, 73 and 97 h post-exercise to the exercised muscles. Maximum voluntary isometric contraction (MVC) torque, muscle soreness, plasma creatine kinase activity, and proprioception assessed by position sense, joint reaction angle, and force match were measured before, and 0.5, 24, 48, 72, 96 and 120 h post-exercise. The outcome measures showed significant changes (P < 0.05) at 0.5-hour post-exercise (before treatment) similarly (P > 0.05) between the conditions in both studies. However, changes in all measures at 24-120 h post-exercise were smaller (P < 0.05) for the FIR than sham condition in both studies. For example, MVC torque returned to the baseline by 72 h post-exercise for the FIR condition in both studies, but was still 19 ± 6% (Study 1) or 17 ± 12% (Study 2) lower than the baseline at 120 h post-exercise for the sham condition. These results suggested that the FIR lamp therapy was effective for accelerating recovery from muscle damage.

FIR lamp therapy was effective for recovering muscle strength and proprioception 1­3 days faster to the baseline.FIR lamp therapy was effective for attenuating muscle soreness by 55­60%, and reducing peak plasma CK activity by 45­89%.The effects of the FIR lamp therapy appear to be greater than other therapeutic interventions for eccentric exercise-induced muscle damage that have been investigated previously.

Abdominal Crunch Syndrome Creates a -Diagnostic Challenge in Treating a Pilot with Acute Upper -Abdominal Pain.

BACKGROUND: A diagnosis in acute abdomen may remain elusive especially when the cause is rare. We report this interesting case of a fighter pilot presenting with acute abdominal pain. The case posed significant challenges in reaching the correct diagnosis of abdominal crunch syndrome. The syndrome is rare with only seven reports in the literature so far. To the best of our knowledge, this is the first ever report of this condition in an aircrew.CASE REPORT: A 37-yr-old pilot presented with severe upper abdominal pain and sweating. During examination, he developed bradycardia and was admitted with a presumptive diagnosis of acute coronary syndrome. Investigations revealed no myocardial ischemia on ECG, transaminitis, raised CPK, CKMB, and LDH. A CECT scan of chest and abdomen was normal. A GI surgery consult was sought where we connected the transaminitis and raised CPK and considered the possibility of rhabdomyolysis. On specific inquiry, the aviator gave history of unaccustomed exercise with a vigorous session of abdominal crunches a day prior. Thus, a diagnosis of abdominal crunch syndrome was concluded.DISCUSSION: The aviator did not associate his vigorous exercise with the occurrence of pain and, therefore, did not mention it. It would have avoided unnecessary investigations and delay in treatment. From the aeromedical safety aspect, had the aviator flown on the day he developed pain, there was a possibility of developing severe pain exacerbated by the G force and G suit and sudden in-flight incapacitation. From the perspective of the aircrew, it is advisable that they avoid sudden, unaccustomed exercise.Kumar A, Kaistha S. Abdominal crunch syndrome creates a diagnostic challenge in treating a pilot with acute upper abdominal pain. Aerosp Med Hum Perform. 2023; 94(2):86-89.

Protein Ingestion in Reducing the Risk of Late-Onset Post-Exercise Hypoglycemia: A Pilot Study in Adolescents and Youth with Type 1 Diabetes.

Dietary protein causes dose-dependent hyperglycemia in individuals with type 1 diabetes (T1D). This study investigated the effect of consuming 50 g of protein on overnight blood glucose levels (BGLs) following late-afternoon moderate-intensity exercise. Six participants (3M:3F) with T1D, HbA1c 7.5 ± 0.8% (58.0 ± 8.7 mmol/mol) and aged 20.2 ± 3.1 years exercised for 45 min at 1600 h and consumed a protein drink or water alone at 2000 h, on two separate days. A basal insulin euglycemic clamp was employed to measure the mean glucose infusion rates (m-GIR) required to maintain euglycemia on both nights. The m-GIR on the protein and water nights during the hypoglycemia risk period and overnight were 0.27 ± 043 vs. 1.60 ± 0.66 mg/kg/min (p = 0.028, r = 0.63) and 0.51 ± 0.16 vs. 1.34 ± 0.71 mg/kg/min (p = 0.028, r = 0.63), respectively. Despite ceasing intravenous glucose infusion on the protein night, the BGLs peaked at 9.6 ± 1.6 mmol/L, with a hypoglycemia risk period mean of 7.8 ± 1.5 mmol/L compared to 5.9 ± 0.4 mmol/L (p = 0.028) on the water night. The mean plasma glucagon levels were 51.5 ± 14.1 and 27.2 ± 10.1 ng/L (p = 0.028) on the protein and water night, respectively. This suggests that an intake of protein is effective at reducing the post-exercise hypoglycemia risk, potentially via a glucagon-mediated stimulation of glucose production. However, 50 g of protein may be excessive for maintaining euglycemia.

Effect of exercise-induced bronchoconstriction on the configuration of the maximal expiratory flow-volume curve in adults with asthma.

We determined the effect of exercise-induced bronchoconstriction (EIB) on the shape of the maximal expiratory flow-volume (MEFV) curve in asthmatic adults. The slope-ratio index (SR) was used to quantitate the shape of the MEFV curve. We hypothesized that EIB would be accompanied by increases in SR and thus increased curvilinearity of the MEFV curve. Adult asthmatic ( n  = 10) and non-asthmatic control subjects ( n  = 9) cycled for 6-8 min at 85% of peak power. Following exercise, subjects remained on the ergometer and performed a maximal forced exhalation every 2 min for a total 20 min. In each MEFV curve, the slope-ratio index (SR) was calculated in 1% volume increments beginning at peak expiratory flow (PEF) and ending at 20% of forced vital capacity (FVC). Baseline spirometry was lower in asthmatics compared to control subjects (FEV1 % predicted, 89.1 ± 14.3 vs. 96.5 ± 12.2% [SD] in asthma vs. control; p  < 0.05). In asthmatic subjects, post-exercise FEV1 decreased by 29.9 ± 13.2% from baseline (3.48 ± 0.74 and 2.24 ± 0.59 [SD] L for baseline and post-exercise nadir; p  < 0.001). At baseline and at all timepoints after exercise, average SR between 80 and 20% of FVC was larger in asthmatic than control subjects (1.48 ± 0.02 vs. 1.23 ± 0.02 [SD] for asthma vs. control; p < 0.005). This averaged SR did not change after exercise in either subject group. In contrast, post-exercise SR between PEF and 75% of FVC was increased from baseline in subjects with asthma, suggesting that airway caliber heterogeneity increases with EIB. These findings suggest that the SR-index might provide useful information on the physiology of acute airway narrowing that complements traditional spirometric measures.

Impact of Exercise-Induced Strains and Nutrition on Bone Mineral Density in Spaceflight and on the Ground.

BACKGROUND: Bone mineral density (BMD) is a measure of skeletal health that may foretell disorders like osteoporosis.METHODS: To reduce bone losses on Earth, treatments include exercise, diet, and drugs. Each impact osteoblast and osteoclast activity dictates skeletal remodeling and subsequent BMD changes. BMD loss is a concern during spaceflight. For astronauts, low BMD undermines in-flight tasks and compromises their postflight health.RESULTS: While bisphosphonates exhibited promise as an in-flight bone loss treatment, study results are mixed, and this class of drugs has numerous side-effects. While the role antiresorptive agents play in reducing BMD loss is discussed, this review focuses on exercise-induced strains and nutrition, two in-flight treatments without bisphosphonates' side-effects.DISCUSSION: Evidence supports in-flight exercise and a healthy diet with vitamin D and Ca+2 supplementation to limit BMD loss. This review suggests how exercise and nutrition may limit BMD loss during spaceflight. Also discussed is an in-flight version of the inertial exercise trainer (IET; Impulse Technologies, Knoxville TN). By imparting high bone-strain magnitudes, rates, and frequencies with less mass, footprint, and power needs than other forms of in-flight resistance exercise hardware, the IET warrants inquiry for use aboard future long-term spaceflights.Caruso J, Patel N, Wellwood J, Bollinger L. Impact of exercise-induced strains and nutrition on bone mineral density in spaceflight and on the ground. Aerosp Med Hum Perform. 2023; 94(12):923-933.

The serum irisin response to prolonged physical activity in temperate and hot environments in older men with hypertension or type 2 diabetes.

Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m2) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (Tco) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite Tco not being different between groups, Tco was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury.

Astragalosides Supplementation Enhances Intrinsic Muscle Repair Capacity Following Eccentric Exercise-Induced Injury.

Astragalosides have been shown to enhance endurance exercise capacity in vivo and promote muscular hypertrophy in vitro. However, it remains unknown whether astragalosides supplementation can alter inflammatory response and enhance muscle recovery after damage in humans. We therefore aimed to evaluate the effect of astragalosides supplementation on muscle's intrinsic capacity to regenerate and repair itself after exercise-induced damage. Using a randomized double-blind placebo-controlled cross-over design, eleven male participants underwent 7 days of astragalosides supplementation (in total containing 4 mg of astragalosides per day) or a placebo control, following an eccentric exercise protocol. Serum blood samples and variables related to muscle function were collected prior to and immediately following the muscle damage protocol and also at 2 h, and 1, 2, 3, 5, and 7 days of the recovery period, to assess the pro-inflammatory cytokine response, the secretion of muscle regenerative factors, and muscular strength. Astragalosides supplementation reduced biomarkers of skeletal muscle damage (serum CK, LDH, and Mb), when compared to the placebo, at 1, 2, and 3 days following the muscle damage protocol. Astragalosides supplementation suppressed the secretion of IL-6 and TNF-α, whilst increasing the release of IGF-1 during the initial stages of muscle recovery. Furthermore, following astragaloside supplementation, muscular strength returned to baseline 2 days earlier than the placebo. Astragalosides supplementation shortens the duration of inflammation, enhances the regeneration process and restores muscle strength following eccentric exercise-induced injury.

Systematic Review of Patient-Reported Outcome Measures for Patients with Exercise-Induced Leg Pain.

Background and Objectives: To determine the most commonly used patient-reported outcome measures (PROMs) in exercise-induced leg pain (EILP) and to identify specific PROMs for EILP in order to evaluate their psychometric properties and methodological quality. Materials and Methods: A strategic search was performed in different databases to identify and extract the characteristics of studies based on the use of PROMs in patients with EILP. Specific PROMs were evaluated according to the Terwee et al. and COSMIN criteria. Results: Fifty-six studies were included in the review. The Medial Tibial Stress Syndrome Score (MTSSS), Lower Extremity Functional Scale (LEFS) and Exercise-Induced Leg Pain Questionnaire (EILP-Q) were identified as specific PROMs for EILP. The Visual Analog Scale (VAS) was the most widely used instrument in the assessment of EILP. The methodological quality assessment showed six positive values for the LEFS, four for the MTSSS and three for the EILP-Q for the eight psychometric properties analyzed according to the COSMIN criteria. The evaluation of the nine psychometric properties according to Terwee showed five positive values for the LEFS and MTSSS, and three for the EILP-Q. Conclusions: The overall methodological quality of the PROMs used was low. The VAS was the most widely used instrument in the assessment of EILP, and the LEFS was the highest quality PROM available for EILP, followed by the MTSSS and EILP-Q, respectively.

Effect of curcumin supplementation on exercise-induced muscle damage: a narrative review.

Curcumin, a natural polyphenol extracted from turmeric, is a potent antioxidant and anti-inflammatory agent. In the past few decades, curcumin's ability to impact chronic inflammatory conditions such as metabolic syndrome, arthritis, and cancer has been widely researched, along with growing interest in understanding its role in exercise-induced muscle damage (EIMD). EIMD impacts individuals differently depending on the type (resistance exercise, high-intensity interval training, and running), intensity, and duration of the exercise. Exercise disrupts the muscles' ultrastructure, raises inflammatory cytokine levels, and can cause swelling in the affected limb, a reduction in range of motion (ROM), and a reduction in muscular force-producing capacity. This review focuses on the metabolism, pharmacokinetics of various brands of curcumin supplements, and the effect of curcumin supplementation on EIMD regarding muscle soreness, activity of creatine kinase (CK), and production of inflammatory markers. Curcumin supplementation in the dose range of 90-5000 mg/day can decrease the subjective perception of muscle pain intensity, increase antioxidant capacity, and reduce CK activity, which reduces muscle damage when consumed close to exercise. Consumption of curcumin also improves muscle performance and has an anti-inflammatory effect, downregulating the production of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-8. Curcumin may also improve oxidative capacity without hampering training adaptations in untrained and recreationally active individuals. The optimal curcumin dose to ameliorate EIMD is challenging to assess as its effect depends on the curcumin concentration in the supplement and its bioavailability.

Safety of an inactivated COVID-19 vaccine in patients with - wheat-dependent exercise-induced anaphylaxis.

BACKGROUND: Inactivated vaccines against coronavirus disease-2019 (COVID-19) offer an effective public health intervention to mitigate this devastating pandemic. However, little is known about their safety in patients with wheat-dependent exercise-induced anaphylaxis (WDEIA). METHODS: We recruited 72 WDEIA patients and 730 healthy matched controls who received an inactivated COVID-19 vaccine. Participants were monitored for 4 weeks after each immunization for adverse reactions and completed questionnaires regarding local and systemic reactions at 7 and 28 days after each vaccination. For those who had received the COVID-19 vaccine prior to enrollment, adverse event data were obtained retrospectively. RESULTS: Local and systemic adverse events occurred at similar rates in the WDEIA group and the control group. In both groups, injection-site pain and fatigue were the most common local and systemic reactions, respectively. Compared with healthy controls, more allergic events were reported in the WDEIA group (after dose 1, 0.5% vs. 4.2%, p=0.019; after dose 2, 0% vs. 1.4%, p=0.089). Allergic reactions mainly manifested as rash, urticaria, and edema, which were mild and controllable. No serious allergic events were reported. CONCLUSIONS: The adverse event profile of inactivated COVID-19 vaccine did not differ between WDEIA patients and healthy controls. The risk of allergic reactions in patients with WDEIA seems higher, but no anaphylaxis was reported, and the allergic reactions were controllable. Inactivated COVID-19 vaccines appear to be well-tolerated in WDEIA patients, but patients with potential allergy risks should be cautious.

Traditional Chinese medicine Jianpi therapy in exercise-induced fatigue: A protocol for systematic review and meta-analysis.

BACKGROUND: Exercise-induced fatigue (EIF) is a common occurrence in sports competition and training. It may cause trouble to athletes' motor skill execution and cognition. Although traditional Chinese medicine Jianpi therapy has been commonly used for EIF management, relevant evidence on the effectiveness and safety of Jianpi therapy is still unclear. METHODS: Databases including PubMed, Embase, Web of Science, the Cochrane Library, SinoMed, China Science and Technology Journal Database (VIP), China National Knowledge Infrastructure (CNKI), and Wanfang will be searched for relevant randomized controlled trials from databases from 2000 to 2021. Randomized controlled trials related to traditional Chinese medicine Jianpi therapy in the treatment and management of EIF will be included. Systematic review and meta-analysis of the data will be performed in RevMan 5.3 according to the Preferred Reporting Items of Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Two authors independently performed the literature searching, data extraction, and quality evaluation. Risk of bias was assessed using the Cochrane Risk of Bias Tool for randomized clinical trials. RESULTS: This systematic review and meta-analysis will summarize the latest evidence for traditional Chinese medicine Jianpi therapy in EIF. The results will be submitted to a peer-reviewed journal once completed. CONCLUSION: The conclusion of our research will provide evidence to support traditional Chinese medicine Jianpi therapy as an effective intervention for patients with EIF.OSF Registration DOI: 10.17605/OSF.IO/NRKX4.

Individualized Studies of Triggers of Paroxysmal Atrial Fibrillation: The I-STOP-AFib Randomized Clinical Trial.

Importance: Atrial fibrillation (AF) is the most common arrhythmia. Although patients have reported that various exposures determine when and if an AF event will occur, a prospective evaluation of patient-selected triggers has not been conducted, and the utility of characterizing presumed AF-related triggers for individual patients remains unknown. Objective: To test the hypothesis that n-of-1 trials of self-selected AF triggers would enhance AF-related quality of life. Design, Setting, and Participants: A randomized clinical trial lasting a minimum of 10 weeks tested a smartphone mobile application used by symptomatic patients with paroxysmal AF who owned a smartphone and were interested in testing a presumed AF trigger. Participants were screened between December 22, 2018, and March 29, 2020. Interventions: n-of-1 Participants received instructions to expose or avoid self-selected triggers in random 1-week blocks for 6 weeks, and the probability their trigger influenced AF risk was then communicated. Controls monitored their AF over the same time period. Main Outcomes and Measures: AF was assessed daily by self-report and using a smartphone-based electrocardiogram recording device. The primary outcome comparing n-of-1 and control groups was the Atrial Fibrillation Effect on Quality-of-Life (AFEQT) score at 10 weeks. All participants could subsequently opt for additional trigger testing. Results: Of 446 participants who initiated (mean [SD] age, 58 [14] years; 289 men [58%]; 461 White [92%]), 320 (72%) completed all study activities. Self-selected triggers included caffeine (n = 53), alcohol (n = 43), reduced sleep (n = 31), exercise (n = 30), lying on left side (n = 17), dehydration (n = 10), large meals (n = 7), cold food or drink (n = 5), specific diets (n = 6), and other customized triggers (n = 4). No significant differences in AFEQT scores were observed between the n-of-1 vs AF monitoring-only groups. In the 4-week postintervention follow-up period, significantly fewer daily AF episodes were reported after trigger testing compared with controls over the same time period (adjusted relative risk, 0.60; 95% CI, 0.43- 0.83; P < .001). In a meta-analysis of the individualized trials, only exposure to alcohol was associated with significantly heightened risks of AF events. Conclusions and Relevance: n-of-1 Testing of AF triggers did not improve AF-associated quality of life but was associated with a reduction in AF events. Acute exposure to alcohol increased AF risk, with no evidence that other exposures, including caffeine, more commonly triggered AF. Trial Registration: ClinicalTrials.gov Identifier: NCT03323099.

The Effect of Nitrate-Rich Beetroot Juice on Markers of Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Human Intervention Trials.

This systematic review and meta-analysis of randomized controlled trials examined whether dietary nitrate supplementation attenuates exercise-induced muscle damage (EIMD) and is reported according to the PRISMA guidelines. Medline and SPORTDiscus databases were searched from inception to June 2020. Inclusion criteria were studies in adult humans consuming inorganic nitrate before and after exercise and that measured markers implicated in the etiology of EIMD (muscle function, muscle soreness, inflammation, myocellular protein efflux, oxidative stress, range of motion) <168 h post. The Cochrane Collaboration risk of bias two tool was used to critically appraise the studies; forest plots were generated with random-effects models and standardized mean differences (SMD). Nine studies were included in the systematic review and six in the meta-analysis. All studies were rated to have some concerns for risk of bias. All trials in the meta-analysis provided nitrate as beetroot juice, which accelerated isometric strength recovery 72 h post-exercise (SMD: 0.54, p = 0.01) and countermovement jump performance 24-72 h post-exercise (SMD range: 0.75-1.32, p < 0.03). Pressure pain threshold was greater with beetroot juice 48 (SMD: 0.58, p = 0.03) and 72 h post-exercise (SMD: 0.61, p = 0.02). Beetroot juice had no effect on markers of oxidative stress and creatine kinase (p > 0.05), but c-reactive protein was higher vs. placebo at 48 h post-exercise (SMD: 0.55, p = 0.03). These findings suggest that nitrate-rich beetroot juice may attenuate some markers of EIMD, but more large-scale controlled trials in elite athletes are needed.

Heart rate variability associated with acute exercise challenge in children with sickle cell anaemia.

We examined heart rate variability (HRV) during exercise testing in 20 children with sickle cell anaemia (SCA) and 12 controls. Subjects achieved lower median HRV at peak exercise [standard deviation of R-wave to R-wave intervals (SDNN), 2·3 vs 2·9 ms, P = 0·027; logarithmic transformation of high frequency power (lnHF), 0·9 vs 1·3 ln(ms2 ), P = 0·047] and had lower post-exercise HRV across minute-by-minute analysis of recovery. After adjustment for haemoglobin, fitness and SCA status, subjects had lower HRV at the end of recovery with differences increasing as baseline HRV increased. Further investigation of HRV and exercise safety in SCA is warranted.