Patellofemoral Pain Syndrome Is Associated With Chronic Disease and Allergies in 60 997 Distance Runner Race Entrants: SAFER XXX Study.

OBJECTIVE: Patellofemoral pain syndrome (PFPS) is a common running-related injury. Independent risk factors associated with PFPS have not been described in a large cohort of distance runners. DESIGN: Descriptive, cross-sectional study. SETTING: 21.1 and 56 km Two Oceans Marathon races (2012-2015). PARTICIPANTS: 60 997 race entrants. ASSESSMENT OF RISK FACTORS: Participants completed a compulsory prerace medical screening questionnaire (history of PFPS in the past 12 months, n = 362; no injury history, n = 60 635). Selected risk factors associated with a history of PFPS were explored using univariate & multivariate analyses: demographics, training/running variables, history of chronic diseases (composite chronic disease score), and any allergy. MAIN OUTCOME MEASURES: Prevalence ratios (PRs, 95% confidence intervals). RESULTS: Risk factors associated with PFPS (univariate analysis) were increased years of recreational running (PR = 1.09; P = 0.0107), older age (>50 years), and chronic diseases (PR > 2): gastrointestinal disease (PR = 5.06; P < 0.0001), cardiovascular disease (CVD) (PR = 3.28; P < 0.0001), nervous system/psychiatric disease (PR = 3.04; P < 0.0001), cancer (PR = 2.83; P = 0.0005), risk factors for CVD (PR = 2.42; P < 0.0001), symptoms of CVD (PR = 2.38; P = 0.0397), and respiratory disease (PR = 2.00; P < 0.0001). Independent risk factors (multivariate analysis) associated with PFPS (adjusted for age, sex, and race distance) were a higher chronic disease composite score (PR = 2.68 increased risk for every 2 additional chronic diseases; P < 0.0001) and a history of allergies (PR = 2.33; P < 0.0001). CONCLUSIONS: Novel independent risk factors associated with PFPS in distance runners are a history of multiple chronic diseases and a history of allergies. Identification of chronic diseases and allergies should be considered as part of the clinical assessment of a runner presenting with a history of PFPS.

Should We Lose Sleep Over Sleep Disturbances After Sports-Related Concussion? A Scoping Review of the Literature.

OBJECTIVE: A single, severe traumatic brain injury can result in chronic sleep disturbances that can persist several years after the incident. In contrast, it is unclear whether there are sleep disturbances after a sports-related concussion (SRC). Considering growing evidence of links between sleep disturbance and neurodegeneration, this review examined the potential links between diagnosed SRCs and sleep disturbances to provide guidance for future studies. METHODS: The scoping review undertook a systematic search of key online databases (Scopus, MEDLINE, SportDiscus, and Web of Science) using predetermined search terms for any articles that examined sleep after concussion. A screening criterion using agreed inclusion and exclusion criteria was utilized to ensure inclusion of relevant articles. DESIGN: This scoping review is guided by the PRSIMA Scoping Review report. RESULTS: Ten studies met the inclusion criteria, reporting on 896 adults who had experienced an SRC. Comparison with 1327 non-SRC adults occurred in 8 studies. Nine studies subjectively examined sleep, of which all but one study reported sleep disturbances after an SRC. Three studies objectively measured sleep, with 2 studies indicating large coefficients of variation of sleep duration, suggesting a range of sleep responses after an SRC. The only study to examine overnight polysomnography showed no differences in sleep metrics between those with and without an SRC. No studies examined interventions to improve sleep outcomes in people with concussion. CONCLUSIONS: This scoping review indicates preliminary evidence of sleep disturbances following an SRC. The heterogeneity of methodology used in the included studies makes consensus on the results difficult. Given the mediating role of sleep in neurodegenerative disorders, further research is needed to identify physiological correlates and pathological mechanisms of sleep disturbances in SRC-related neurodegeneration and whether interventions for sleep problems improve recovery from concussion and reduce the risk of SRC-related neurodegeneration.

Longer race distance predicts gastrointestinal illness-related medical encounters in 153,208 endurance runner race starters - SAFER XVI.

BACKGROUND: Gastrointestinal illness-related (GITill) medical encounters during distance running range from mild to debilitating. The objective of this study was to identify factors that may predict GITill among 21.1 km and 56 km race starters. METHODS: This is a cross-sectional analysis of data collected prospectively over 8 years at the Two Oceans 56 km and 21.1 km races with 153,208 race starters. GITill encounters requiring medical attention on race day were recorded by medical staff. Risk factors associated with GITill explored in univariate models included: race distance (21.1 km; 56 km), sex, age group, running experience, running speed, and environmental factors (wet-bulb temperature, wind speed and humidity). Incidence (per 100,000 race starters; 95% CI) and incidence ratios (IR) (with 95% CI) are reported. RESULTS: The incidence of GITill encounters was 60 (95%CI: 50-80) (1/1667 race starters). A longer race distance (56 km vs. 21.1 km) was the strongest predictor of GITill (IR=4.3; 95% CI: 2.7-6.7) (P<0.0001). Among the 56 km race starters, slower running speed (km/h) was a predictor of GITill (IR=1.63; 95%CI:1.2-2.3) (P=0.0024). Neither age group, nor running experience or any environmental factors (wet-bulb temperature, wind speed, humidity) were associated with a higher risk of GITill. CONCLUSIONS: Medical teams, responsible for care at longer race distances, can expect a higher incidence of GITill that require medical attention compared with shorter race distances. Slower runners competing in ultramarathons are a subgroup at higher risk of GITill. These data can assist medical teams at events to improve and plan medical care, target runner education and establish prevention strategies to reduce GITill in runners.

Cardiovascular response to whole-body vibration on an automobile seat.

The study aim was to determine whether a relationship exists between the cardiovascular response, measured by HR and HRV and the magnitude of whole-body vibration. Cardiovascular response of sixty male participants in four groups, was measured during three states i.e. (1) no vibration, (2) a reference vibration and (3) an alternative vibration. The reference vibration was the same for all groups with the alternative vibrations different for each group. Weighted vertical seat vibration was 0.66 m.s-2, root-mean-square for the reference and 0.70, 0.73, 0.76, and 0.79 m.s-2, root-mean-square for the alternative vibrations. Vibrations only differed in magnitude with the difference between alternative vibrations based on relative difference thresholds. Nonparametric tests compared cardiovascular indicators between groups at State 3 adjusted for state of departure i.e. State 2. No significant differences between groups were found for most of the indicators, suggesting no relationship between cardiovascular response and the magnitude of whole-body vibration. Practitioner summary: The cardiovascular response to the magnitude of whole-body vibration on an automobile seat was investigated. Results suggest that no relationship exists between the magnitude and cardiovascular response and that the latter may not be as effective as other objective measures (e.g. acceleration) in evaluating the human's response to whole-body vibration.

Arabic translation and cross-cultural adaptation of the Sport Concussion Assessment Tool 5 (SCAT5).

The aim was to create a Modern Standard Arabic SCAT5 version for different Arabic dialects. This translation and cross-cultural adaptation was performed in eight stages: initial translations, reconciliation of translations and cultural adaptation, back translation, appraisal of back translations, validation of the translation, review and adjustment by reconciliation committee, pretesting in 12 football players and document finalisation. As an alternative to the problematic Months In Reverse Order Test (MIROT) in Arabic, the Serial 3s test (32 Arabic and 30 English participants), the Days of the Week Backwards test (DWBT), and the 'Adding Serial 3s' test were tested (30 English and 30 Arabic participants) for accuracy, difficulty and time of completion. The Arabic SCAT5 was similar and comparable to the original English version (7-point Likert scales =< 2). Testing of the pre-final version of the Arabic SCAT5 took 20.4 (SD 3.4) and 17.7 (SD 3.0) minutes respectively to complete and was found acceptable in terms of clarity, understandability, grammatical correctness and coherence. The Arabic Serial 3s test (subtraction version) was unsuitable due to high completion time, low pass rate and high difficulty perception [time = 47.2 (SD 28.0) s; accuracy = 55.2%; difficulty = 3.2 (SD 1.1)]. The Arabic DWBT was too fast and undemanding for concentration testing [time = 4.6 (SD 1.5) s; accuracy = 90%; difficulty = 1.1 (SD 0.3)]. The Adding Serial 3s tests produced similar completion times [18.4 (SD 6.8) vs. 21.1 (SD 5.3), p = 0.088], accuracy (100%) and self-rated difficulty [English = 2.0 (SD 0.7) vs. Arabic-speaking participants = 2.1 (SD 0.8), p = 0.512] and was therefore adopted to replace the MIROT. This culturally adapted Arabic-SCAT5 questionnaire is the first concussion assessment tool available for Arabic-speaking healthcare providers and athletes. Sport Concussion Assessment Tool 5 (SCAT5). Biol Sport. 2021;38(1):129-144.

One in four trail running race entrants sustained an injury in the 12 months training preceding the 2019 SkyRun race.

OBJECTIVE: To determine the epidemiology and clinical characteristics of RRIs among trail runners who entered the 2019 SkyRun races. DESIGN: Descriptive cross-sectional study. SETTING: 2019 SkyRun races. PARTICIPANTS: Consent for data analysis was given by 305 of 412 (74%) race entrants. MAIN OUTCOME MEASURES: Retrospective annual incidence (RRIs/1000 h), point prevalence (%), frequency (%), characteristics (anatomical region, body area, tissue type, pathology type) and injury severity (mean severity score; 95% CI) of RRIs. RESULTS: 28.2% of participants reported at least one RRI. The retrospective annual incidence was 49.5 RRIs per 1000h and the point prevalence was 1.3%. Most injuries occurred in the lower limb (87.3%), with the knee (26.5%), ankle (21.6%), and foot (16.7%) reported as the most frequently injured body areas. Muscle/tendon accounted for 44.1% of tissue type injuries. Tendinopathy (27.5%), joint sprain (19.6%), and muscle injury (15.7%) were the most common pathology types reported. The mean injury severity score was 31.6. CONCLUSIONS: One in 4 trail runners reported at least one RRI in the 12 months leading up to a race. RRIs mostly affected the lower limb specifically the knee, ankle and foot. Future research should establish injury risk factors to ultimately develop specific injury prevention strategies.

The Injury and Illness Profile of Male and Female Participants in a 94.7 km Cycle Race: A Cross-Sectional Study.

OBJECTIVE: To describe the incidence and patterns of injury and illness of male and female participants during a 94.7 km distance cycling event. DESIGN: Descriptive study. SETTING: Momentum 94.7 Cycle Challenge 2014. PARTICIPANTS: All 23 055 race starters (males = 17 520, females = 5236, not specified = 299). MAIN OUTCOME MEASURES: The incidence and type of all medical complaints and difference between sexes. RESULTS: Incidence (per 1000 race starters) of all medical complaints was 38.69 (males = 36.52, females = 38.39), adverse medical events 11.88 (males = 10.73, females = 16.42) and serious adverse events 1.3 (males = 0.86, females = 2.67). The incidence of nontraumatic medical complaints was 32.49 (males = 33.39, females = 31.32) and of traumatic injuries was 3.99 (males = 3.14, females = 7.07). Females compared to males had a higher risk of sustaining traumatic injuries (P < 0.001), central nervous system, (P = 0.0062) and eye complaints (P = 0.0107). Most complaints (80.6%) were reported for the musculoskeletal system. Males 10-15 years (P = 0.0013) and females 23-39 years (P = 0.0336), and older than 50 years (P = 0.0002) had a higher than expected risk for traumatic injuries. CONCLUSIONS: Medical complaints ratio reported was 1:26 (males = 1:28, females = 1:26) in all starters during the cycling event. Cyclists that did not finish the race (adverse events) were 1:84 (males = 1:93, females = 1:61). Serious adverse events that required hospitalization were 1:769 (males = 1:1163, females = 1:374). The majority of admissions were for traumatic injuries, followed by cardiovascular complaints. Results from this study indicated that a wide spectrum of medical complaints can be expected during such an event with a higher risk for females to sustain traumatic injuries and to encounter central nervous system and eye complaints. Information regarding the pattern and type of medical encounters can prove useful during planning and management of similar future events.

Effect of Mixed Basic Military Training on the Physical Fitness of Male and Female Soldiers.

INTRODUCTION: Mixed gender basic military training (BMT) is adopted to integrate the female South African soldier into the military. This study aimed to assess gender differences before, during (12 weeks), and after a 20-week mixed BMT course and determine if BMT significantly reduced these differences. METHODS: A total of 186 soldiers (114 male: mean age = 21.0 ± 1.1 year; 72 female: mean age = 20.5 ± 1.2 year) completed the BMT course and all anthropometric, physical fitness, explosive power, and hand grip strength measurements. Repeated-measures analysis of variance was used to model BMT data with main effects for gender comparison between males and females, and time main effect for evaluation of differences between weeks 1, 12, and 20 of BMT, as well as an interaction effect for differences in changes over time for males and females. Alpha was set at α ≤0.05. RESULTS: Male soldiers were significantly taller (p < 0.001) and scored better in all measurements at the start of BMT, differences ranged from 1.6% to 50% between genders. Differences narrowed by up to 18.5% in aerobic, push-up, abdominal measurements, and to 4.6% in the South African National Defense Force fitness test. Differences in power output and hand grip strength remained unchanged. CONCLUSION: Large initial anthropometrical and physical fitness differences decreased but were still obvious at the end of BMT. BMT should bridge the physical gap between male and female soldiers to ensure they can all perform the same duties. The enforcing of equal minimum physical fitness requirements for acceptance into BMT; conditional acceptance into the military subject to the successful completion of a bridging course aimed at improving physical fitness in individuals who do not meet the minimum physical fitness requirements for acceptance; and developing a cyclic physical training program with different entry points, dependent on initial physical performance at the start of BMT, ensuring adequate progression and overload for all soldiers are possible avenues to explore to achieve this goal.

The Difference Between Exercise-Induced Autonomic and Fitness Changes Measured After 12 and 20 Weeks of Medium-to-High Intensity Military Training.

Grant, CC, Mongwe, L, Janse van Rensburg, DC, Fletcher, L, Wood, PS, Terblanche, E, and du Toit, PJ. The difference between exercise-induced autonomic and fitness changes measured after 12 and 20 weeks of medium-to-high intensity military training. J Strength Cond Res 30(9): 2453-2459, 2016-The aim of this study was to compare the physical fitness, based on VO2max and exercise-induced cardiac autonomic changes, measured by heart rate variability (HRV) of 12 weeks with 20 weeks of training in the South African National Defence Force. Recruits (n = 154) participated in a medium-to-high intensity exercise intervention (daily energy expenditure: 8,485 kJ·d). The significant effect on VO2max between weeks 1 and 12 (48.57, SD = 9.25 vs. 53.36, SD = 7.21] did not continue during weeks 12-20 (53.36, SD = 7.21 vs. 53.87, SD = 7.87). No changes in the supine low frequency (LF)/high frequency (HF) (0.48, SD = 0.51 vs. 0.41, SD = 0.64) or the standing LF/HF (4.02, SD = 5.14 vs. 3.91, SD = 5.28), an indicator of autonomic balance and a possible indicator of overtraining syndrome, suggests that overtraining did not take place during weeks 12-20. This was confirmed with further decreases in supine and standing heart rate. However, the power of the vagal-induced variability continued to increase after 12 weeks. Increased vagal influence without concurrent change in autonomic balance may be interpreted as decreased sympathetic cardiac control. It is important to note that although no fitness changes were detected, positive cardiac autonomic conditioning did continue between weeks 12 and 20, as measured by increased vagal-induced HRV and decreased sympathetic influence on cardiac control. Results may be extrapolated to training in the normal population/athletes after a medium-to-high intensity exercise program, as this intervention was a closely monitored and standardized exercise program.

Ultra-Marathon Athletes at Risk for the Female Athlete Triad.

BACKGROUND: Worldwide female participation in ultra-endurance events may place them at risk for the female athlete triad (FAT). The study objectives were to establish triad knowledge, occurrence of disordered eating and triad risk amongst participants of the 2014 89-km Comrades Marathon event. METHODS: A survey utilising the Low Energy Availability in Females questionnaire (LEAF-Q) and Female Athlete Screening Tool (FAST) questionnaire was conducted on female participants in order to determine the risk. In addition, seven questions pertaining to the triad were asked in order to determine the athlete's knowledge of the triad. Athletes were requested to complete the anonymous questionnaire after written informed consent was obtained while waiting in the event registration queues. Statistical analyses included Pearson product-moment correlations, chi-square tests and cross-tabulations to evaluate associations of interest. RESULTS: Knowledge of the triad was poor with 92.5 % of participants having not heard of the triad before and most of those who had, gained their knowledge from school or university. Only three athletes were able to name all 3 components of the triad. Amenorrhoea was the most commonly recalled component while five participants were able to name the component of low bone mineral density. Of the 306 athletes included in the study, 44.1 % were found to be at risk for the female athlete triad. One-third of participants demonstrated disordered eating behaviours with nearly half reporting restrictive eating behaviours. There is a significant association between athletes at risk for the triad according to the LEAF-Q and those with disordered eating (χ2(1) = 8.411, p = 0.014) but no association (or interaction) between triad knowledge and category (at risk/not at risk) of LEAF-Q score (χ2(1) = 0.004, p = 0.949). More athletes in the groups with clinical and sub-clinical eating disorders are at risk for the triad than expected under the null hypothesis for no association. CONCLUSIONS: Only 7.5 % of the female Comrades Marathon runners knew about the triad despite 44.1 % being at a high risk for the triad. Therefore, education and regular screening programmes targeting these athletes are overdue. Postmenopausal athletes are at particularly high risk for large losses in bone mass if they experience chronic energy deficiency and hence require special focus.

Iliac artery endofibrosis in a middle-aged female long-distance runner.

Exercise-induced iliac artery endofibrosis is a recently described abnormality of the external iliac artery that typically affects younger, healthy endurance athletes. Characteristic of the initially termed cyclist's iliac syndrome is lower limb pain during exercise with rapid recovery after exercise. This clinically complicated case describes an older female long-distance runner in whom an incorrect diagnosis of fibromuscular dysplasia was originally made when she presented with claudication and thrombosis of the right external iliac artery. A thrombectomy and bilateral balloon angioplasty were performed; however, her symptoms persisted. Four months later, she unexpectedly complained of dual calf claudication, a diagnosis of exercise-induced iliac artery endofibrosis was made, and a bilateral prosthetic graft bypass procedure was performed, which resulted in a good outcome.

Herbaceous forage and selection patterns by ungulates across varying herbivore assemblages in a South African Savanna.

Herbivores generally have strong structural and compositional effects on vegetation, which in turn determines the plant forage species available. We investigated how selected large mammalian herbivore assemblages use and alter herbaceous vegetation structure and composition in a southern African savanna in and adjacent to the Kruger National Park, South Africa. We compared mixed and mono-specific herbivore assemblages of varying density and investigated similarities in vegetation patterns under wildlife and livestock herbivory. Grass species composition differed significantly, standing biomass and grass height were almost twice as high at sites of low density compared to high density mixed wildlife species. Selection of various grass species by herbivores was positively correlated with greenness, nutrient content and palatability. Nutrient-rich Urochloa mosambicensis Hack. and Panicum maximum Jacq. grasses were preferred forage species, which significantly differed in abundance across sites of varying grazing pressure. Green grasses growing beneath trees were grazed more frequently than dry grasses growing in the open. Our results indicate that grazing herbivores appear to base their grass species preferences on nutrient content cues and that a characteristic grass species abundance and herb layer structure can be matched with mammalian herbivory types.

A comparison between heart rate and heart rate variability as indicators of cardiac health and fitness.

Quantification of cardiac autonomic activity and control via heart rate (HR) and heart rate variability (HRV) is known to provide prognostic information in clinical populations. Issues with regard to standardization and interpretation of HRV data make the use of the more easily accessible HR on its own as an indicator of autonomic cardiac control very appealing. The aim of this study was to investigate the strength of associations between an important cardio vascular health metric such as VO2max and the following: HR, HRV indicators, and HR normalized HRV indicators. A cross sectional descriptive study was done including 145 healthy volunteers aged between 18 and 22 years. HRV was quantified by time domain, frequency domain and Poincaré plot analysis. Indirect VO2max was determined using the Multistage Coopers test. The Pearson correlation coefficient was calculated to quantify the strength of the associations. Both simple linear and multiple stepwise regressions were performed to be able to discriminate between the role of the individual indicators as well as their combined association with VO2max. Only HR, RR interval, and pNN50 showed significant (p < 0.01, p < 0.01, and p = 0.03) correlations with VO2max. Stepwise multiple regression indicated that, when combining all HRV indicators the most important predictor of cardio vascular fitness as represented by VO2max, is HR. HR explains 17% of the variation, while the inclusion of HF (high frequency HRV indicator) added only an additional 3.1% to the coefficient of determination. Results also showed when testing the normalized indicators, HR explained of the largest percentage of the changes in VO2max (16.5%). Thus, HR on its own is the most important predictor of changes in an important cardiac health metric such as VO2max. These results may indicate that during investigation of exercise ability (VO2max) phenomena, quantification of HRV may not add significant value.

The contribution of preintervention blood pressure, VO2max, BMI, autonomic function and gender to exercise-induced changes in heart rate variability.

INTRODUCTION: The quantification of heart rate variability (HRV) is a tool to assess the interaction between exercise and autonomic control, as well as the pathophysiology of diseases affecting autonomic function. Little is known about the influence of genetically influenced physiology on exercise-induced changes in autonomic cardiac regulation. It was theorised that preintervention values for blood pressure, VO2max, body mass index (BMI), autonomic function and gender contribute significantly to the exercise-induced changes in HRV. METHODS: A 12-week, medium-to-high intensity exercise intervention was completed by 183 volunteers (18-22 years). Data were sampled at baseline and after 12 weeks. Standard time domain, frequency domain and Poincaré HRV quantification techniques were implemented. Regression analysis was performed to determine the influences of the predictors (baseline values for low frequency  (LF), high frequency (HF), BMI, VO2max, gender, blood pressure) on the exercise-induced response of the dependent variables (changes in HRV-indicator values). RESULTS: Parameters found to be significant (p<0.05) predictors of exercise-induced changes were LF, HF and systolic blood pressure in, respectively, 10, 5 and 2 of the 12 regressions performed. The results indicated that the independent variables contribute between 12.83% and 29.82%, depending on the specific HRV indicator, to the exercise-induced changes in the autonomic nervous system. CONCLUSIONS: Preintervention autonomic status, as represented specifically by LF, is the most important determinant of cardiac autonomic response to an exercise intervention in a healthy study population. Baseline autonomic function could thus be a significant confounder in the outcome of exercise study results.

Autonomic impairment in rheumatoid arthritis.

AIM: To determine if there is a difference between autonomic cardiac control as measured by heart rate variability (HRV) in women with rheumatoid arthritis (RA) compared to a healthy control group. METHODS: The RA group (45) and control group (39) were matched for age and body mass index (BMI). Three techniques were used: time domain, frequency domain and Poincarè plot analysis. All possible confounding factors were excluded and the test environment strictly regulated. RESULTS: Basal heart rate was significantly higher in the RA patients. In the supine position significant differences existed between RA patients and controls (P ≤ 0.01). Indicators of parasympathetic activity showed significantly lower variation in the RA group (root mean square of the standard deviation [RMSSD] = 14.70, percentage of successive normal-to-normal interval differences larger than 50 ms [pNN50] = 0.50, standard deviation [SD]1 = 10.50, high frequency [HF] (ms(2)) = 31) compared to controls (RMSSD = 29.40, pNN50 = 7.8, SD1 = 20.9, HF (ms(2)) = 141.00). Indicators of sympathetic variation were also significantly lower in RA patients (SD2 = 36.70, low frequency [LF] (ms(2)) = 65) compared to controls (SD2 = 49.50, LF (ms(2)) = 175). In the standing position eight variables indicated autonomic impairment by significant differences (P ≤ 0.01) between the groups. The response of the RA group to an orthostatic stressor showed less vagal withdrawal, (P-values for RMSSD = 0.038, pNN50 = 0.022, SD1 = 0.043 and HF [ms(2) ] = 0.008 respectively); and lower sympathetic response (P-values for SD2 = 0.001 and LF [ms(2) ] < 0.001) when compared to controls. CONCLUSIONS: An inability of the autonomic nervous system to efficiently compensate for internal and external environmental changes may predispose RA patients to arrhythmias, thereby increasing cardiovascular mortality. All three methods used showed the same outcome, implying decreased HRV and thus an increased risk for arrhythmias in RA patients. Evaluating the autonomic nervous system might be critical in planning management of RA patients.

Heart rate variability assessment of the effect of physical training on autonomic cardiac control.

BACKGROUND: The effect of exercise interventions on autonomic nervous system (ANS) control of the heart by heart rate variability (HRV) is often investigated in just one position. It was hypothesized that results of exercise-induced changes on ANS are dependent on body position and that it is possible to distinguish between exercise induced changes in vagal and sympathetic influence by taking measurements in different body positions. METHODS: One hundred eighty-three (male = 100, female = 83) healthy volunteers, between 18 and 22 years, participated in a prospective twelve week medium to high intensity exercise intervention study with a self-control design. The influence of the exercise intervention was investigated on supine, rising, and standing as well as on the orthostatic response. Time domain, frequency domain and nonlinear (Poincaré) HRV analysis were performed. RESULTS: The exercise intervention lead to a significant increase (P < 0.05) in vagal influence during supine, rising, and standing. Sympathetic control in the supine position was decreased and increased during rising and standing. In the initial orthostatic response to rising from the supine position, the exercise intervention lead to increased (P < 0.05) vagal withdrawal as well as increased sympathetic control. The orthostatic response measured as the difference between standing and supine indicated only an exercise induced increase in sympathetic control. CONCLUSIONS: Exercise-induced changes in sympathetic and parasympathetic ANS control differ, depending on posture and period of measurement. Exercise induced changes in parasympathetic and sympathetic outflow, respectively, can be extracted from measurements from supine, through the orthostatic response, to standing, thereby detecting changes in ANS that are otherwise obscured.

Effect of exercise on cardiac autonomic function in females with rheumatoid arthritis.

The objective of this study is to evaluate the effect of exercise on cardiac autonomic function as measured by short-term heart rate variability (HRV) in females suffering from rheumatoid arthritis (RA). Females with confirmed RA were randomly assigned to an exercise group (RAE) and a sedentary group (RAC). RAE was required to train under supervision two to three times per week, for 3 months. Three techniques (time domain, frequency domain and Poincaré plot analyses) were used to measure HRV at baseline and study completion. At baseline, RAC (n = 18) had a significantly higher variability compared to RAE (n = 19) for most HRV indicators. At study completion, the variables showing significant changes (p = 0.01 to 0.05) favoured RAE in all instances. Wilcoxon signed rank tests were performed to assess changes within groups from start to end. RAE showed significant improvement for most of the standing variables, including measurements of combined autonomic influence, e.g. SDRR (p = 0.002) and variables indicating only vagal influence, e.g. pNN50 (p = 0.014). RAC mostly deteriorated with emphasis on variables measuring vagal influence (RMSSD, pNN50, SD1 and HF (ms(2)). Study results indicated that 12 weeks of exercise intervention had a positive effect on cardiac autonomic function as measured by short-term HRV, in females with RA. Several of the standing variables indicated improved vagal influence on the heart rate. Exercise can thus potentially be used as an instrument to improve cardiac health in a patient group known for increased cardiac morbidity.

Importance of tachogram length and period of recording during noninvasive investigation of the autonomic nervous system.

BACKGROUND: Various disciplines use quantification of heart rate variability (HRV) as an indicator of autonomic function without recognizing the importance of using standardized methodologies. The aim of this study was to assess the influence of tachogram length and period of recording on HRV indicator values. METHODS: To test the influence of the length of the recording time, HRV indicator values calculated from 180, 300, 420, and 600 seconds recording periods (supine and standing) were compared. Also individual 3- minute periods (0-180 seconds, 180-360 seconds, 360-540 seconds) from 10-minute (supine and standing) tachograms were compared. RESULTS: In the supine position, vagal-efferent HRV indicators were not influenced by tachogram length varying between 3 and 10 minutes (P > 0.05). Supine HRV indicator values representing combined sympathetic and parasympathetic influences were tachogram length-dependent (P < 0.05). During orthostatic stress all HRV indicators were tachogram length-dependent (P < 0.05). Upon standing up marked vagal withdrawal and sympathetic activation occurred. Vagal withdrawal tapered off during the 3-6-minute period after rising while indicators representing combined vagal and sympathetic activation were totally reversed. CONCLUSIONS: During application of orthostatic stress the exact starting point of recording, as well as the length of recording, is critical due to the activation and normalization of homeostatic mechanisms. Starting the tachogram recording too late will miss out on part of the initial response to change in body position. Longer recording times will give a combination of values recorded during the stress response and values obtained after stabilization in the standing position.

DEXA-assessed regional body composition changes in young female military soldiers following 12-weeks of periodised training.

Dual-energy X-ray absorptiometry (DEXA) was used to assess whole body and regional soft tissue mass, fat mass and lean body mass compositional changes in 68 female recruits (age 20.8 +/- 1.14 years; body mass 59.5 +/- 8.79 kg; stature 159.57 +/- 5.53 cm) pre- and post 12-weeks of military basic training. A decrease in total body fat tissue mass (10.2%) and regional percent fat (10.9%) was measured with an increase in total lean body mass (8.7%). Of interest were the differences in the responses in the tissue composition of the arms (16.2% loss in fat mass with an 11.6% gain in lean mass), trunk (17.0% decrease in fat mass with a 10.4% increase in lean mass) and the legs (10.5% increase in lean mass but no change in fat mass). These findings show the importance of considering regional rather than whole body composition changes when assessing the effects of a training programme. STATEMENT OF RELEVANCE: Female soldiers experienced a change in total body fat tissue (-10.2%) and lean body mass (+8.7%) after basic training; however, no significant fat mass decrease was evident in the leg region. Regional rather than whole body composition changes need to be considered when assessing the effects of a training programme.

Relationship between exercise capacity and heart rate variability: supine and in response to an orthostatic stressor.

The study investigated whether supine-measured HRV indicators, and/or HRV indicators measured during orthostatic stress are related to conventional measures of exercise and performance ability such as VO(2max). Only two significant correlations (p<0.05) out of 30 tests were found between supine-determined HRV indicators and conventional measures. In contrast, fifteen of the 30 relationships calculated during orthostatic stress were significant. Relationships were at best low to moderate (0.2<|corr|<0.4). As expected, the relationships obtained during orthostatic stress were reversed from that obtained in the supine position. In summary, although HRV indicators are related to cardiovascular fitness, correlations between VO(2max) and these parameters are found only under very specific conditions. HRV parameters explain very little of the variance in VO(2max). In addition, estimating the exercise capacity from HRV indicators requires experience and extreme caution.