Polar Heart Rate Monitor Research Articles

A Pilot Study Validating Select Research-Grade and Consumer-Based Wearables Throughout a Range of Dynamic Exercise Intensities in Persons With and Without Type 1 Diabetes: A Novel Approach.

The increasing popularity of wearable technology necessitates the evaluation of their accuracy to differentiate physical activity (PA) intensities. These devices may play an integral role in customizing PA interventions for primary prevention and secondary management of chronic diseases. For example, in persons with type 1 diabetes (T1D), PA greatly affects glucose concentrations depending on the intensity, mode (ie, aerobic, anaerobic, mixed), and duration. This variability in glucose responses underscores the importance of implementing dependable wearable technology in emerging avenues such as artificial pancreas systems. Participants completed three 40-minute, dynamic non-steady-state exercise sessions, while outfitted with multiple research (Fitmate, Metria, Bioharness) and consumer (Garmin, Fitbit) grade wearables. The data were extracted according to the devices' maximum sensitivity (eg, breath by breath, beat to beat, or minute time stamps) and averaged into minute-by-minute data. The variables of interest, heart rate (HR), breathing frequency, and energy expenditure (EE), were compared to validated criterion measures. Compared to deriving EE by laboratory indirect calorimetry standard, the Metria activity patch overestimates EE during light-to-moderate PA intensities (L-MI) and moderate-to-vigorous PA intensities (M-VI) (mean ± SD) (0.28 ± 1.62 kilocalories· minute-1, P < .001, 0.64 ± 1.65 kilocalories· minute-1, P < .001, respectively). The Metria underestimates EE during vigorous-to-maximal PA intensity (V-MI) (-1.78 ± 2.77 kilocalories · minute-1, P < .001). Similarly, compared to Polar HR monitor, the Bioharness underestimates HR at L-MI (-1 ± 8 bpm, P < .001) and M-VI (5 ± 11 bpm, P < .001), respectively. A significant difference in EE was observed for the Garmin device, compared to the Fitmate ( P < .001) during continuous L-MI activity. Overall, our study demonstrates that current research-grade wearable technologies operate within a ~10% error for both HR and EE during a wide range of dynamic exercise intensities. This level of accuracy for emerging research-grade instruments is considered both clinically and practically acceptable for research-based or consumer use. In conclusion, research-grade wearable technology that uses EE kilocalories · minute-1 and HR reliably differentiates PA intensities.

Comparisons of Heart Rate and Energy Expenditure During Exergaming in College-age Adults

Abstract The purpose of this study was twofold: 1) to discover the differences in degree of energy expenditure (EE) during Just Dance 2015 using Xbox 360 Kinect, Wii-U, PS3 Move, and Control YouTube video; and 2) to uncover whether or not exergaming could elicit moderate to vigorous levels of intensity (≥ 40% Heart Rate Reserve (HRR)) based on heart rate average (HRavg) measurements. Twenty-five healthy college-aged students participated in this study. Data collection was comprised of baseline testing, a 30 second familiarization period with each gaming console, and a gaming session. Participants danced to the song “Love Me Again” on a Just Dance 2015 program on Xbox 360 Kinect, Wii-U, PS3 Move, and a control YouTube. EE and HRR were calculated using FT4 Polar Heart Rate Monitor. One-way repeated measures ANOVA indicated no significant differences in energy expenditure across the consoles, F(2.74, 65.86)=0.65, p=.570. The paired samples t-test indicated the HRavg for the Xbox 360 Kinect (117±18 bpm) was significantly greater than the HRavg for the Control (112±16 bpm), t(24)=3.03, p=.006. About a third (28%-36%) of participants met moderate levels of intensity while exergaming. Dancing on all three major gaming consoles and YouTube video increase energy expenditures and can be used as an alternative form of exercise with the ability to achieve moderate levels of intensity.

Fitbit Charge HR Wireless Heart Rate Monitor: Validation Study Conducted Under Free-Living Conditions.

BackgroundMany modern smart watches and activity trackers feature an optical sensor that estimates the wearer’s heart rate. Recent studies have evaluated the performance of these consumer devices in the laboratory.ObjectiveThe objective of our study was to examine the accuracy and sensitivity of a common wrist-worn tracker device in measuring heart rates and detecting 1-min bouts of moderate to vigorous physical activity (MVPA) under free-living conditions.MethodsTen healthy volunteers were recruited from a large university in Singapore to participate in a limited field test, followed by a month of continuous data collection. During the field test, each participant would wear one Fitbit Charge HR activity tracker and one Polar H6 heart rate monitor. Fitbit measures were accessed at 1-min intervals, while Polar readings were available for 10-s intervals. We derived intraclass correlation coefficients (ICCs) for individual participants comparing heart rate estimates. We applied Centers for Disease Control and Prevention heart rate zone cut-offs to ascertain the sensitivity and specificity of Fitbit in identifying 1-min epochs falling into MVPA heart rate zone.ResultsWe collected paired heart rate data for 2509 1-min epochs in 10 individuals under free-living conditions of 3 to 6 hours. The overall ICC comparing 1-min Fitbit measures with average 10-s Polar H6 measures for the same epoch was .83 (95% CI .63-.91). On average, the Fitbit tracker underestimated heart rate measures by −5.96 bpm (standard error, SE=0.18). At the low intensity heart rate zone, the underestimate was smaller at −4.22 bpm (SE=0.15). This underestimate grew to −16.2 bpm (SE=0.74) in the MVPA heart rate zone. Fitbit devices detected 52.9% (192/363) of MVPA heart rate zone epochs correctly. Positive and negative predictive values were 86.1% (192/223) and 92.52% (2115/2286), respectively. During subsequent 1 month of continuous data collection (270 person-days), only 3.9% of 1-min epochs could be categorized as MVPA according to heart rate zones. This measure was affected by decreasing wear time and adherence over the period of follow-up.ConclusionsUnder free-living conditions, Fitbit trackers are affected by significant systematic errors. Improvements in tracker accuracy and sensitivity when measuring MVPA are required before they can be considered for use in the context of exercise prescription to promote better health.

Characterisation of regional skin temperatures in recreational surfers wearing a 2-mm wetsuit

The purpose of this study was to investigate skin temperatures across surfers’ bodies while wearing a wetsuit during recreational surfing. Forty-six male recreational surfers participated in this study. Participants were instrumented with eight wireless iButton thermal sensors for the measurement of skin temperature, a Polar RCX5 heart rate monitor and a 2-mm full wetsuit. Following instrumentation, participants were instructed to engage in recreational surfing activities as normal. Significant differences (p < 0.001) in skin temperature (Tsk) were found across the body while wearing a wetsuit during recreational surfing. In addition, regional skin temperature changed across the session for several regions of the body (p < 0.001), and the magnitude of these changes varied significantly between regions. We show for the first time that significant differences exist in skin temperature across the body while wearing a wetsuit during a typical recreational surfing session. These findings may have implications for future wetsuit design.Practitioner Summary: This study investigated the impact of wearing a wetsuit during recreational surfing on regional skin temperatures. Results from this study suggest that skin temperatures differ significantly across the body while wearing a 2-mm wetsuit during recreational surfing. These findings may have implications for future wetsuit design.

The ExPeCT (Examining Exercise, Prostate Cancer and Circulating Tumour Cells) trial: study protocol for a randomised controlled trial

BackgroundProstate cancer (PrCa) is the second most common cancer in Ireland. Many men present with locally advanced or metastatic cancer for whom curative surgery is inappropriate. Advanced cancer patients are encouraged to remain physically active and therefore there is a need to investigate how patients with metastatic disease tolerate physical activity programmes. Physical activity reduces levels of systemic inflammatory mediators and so an aerobic exercise intervention may represent an accessible and cost-effective means of ameliorating the pro-inflammatory effects of obesity and subsequently decrease poor cancer-specific outcomes in this patient population. This study will assess the feasibility and safety of introducing a structured aerobic exercise intervention to an advanced cancer population. This study will also examine if the evasion of immune editing by circulating tumour cells (CTCs) is an exercise-modifiable mechanism in obese men with prostate cancer.MethodsThis international multicentre prospective study will recruit men with metastatic prostate cancer. Participants will be recruited from centres in Dublin (Ireland) and London (UK). Participants will be divided into exposed and non-exposed groups based on body mass index (BMI) ≥ 25 kg/m2 and randomised to intervention and control groups. The exercise group will undertake a regular supervised aerobic exercise programme, whereas the control group will not. Exercise intensity will be prescribed based on a target heart rate monitored by a polar heart rate monitor. Blood samples will be taken at recruitment and at 3 and 6 months to examine the primary endpoint of platelet cloaking of CTCs. Participants will complete a detailed questionnaire to assess quality of life (QoL) and other parameters at each visit.DiscussionThe overall aim of the ExPeCT trial is to examine the relationship between PrCa, exercise, obesity, and systemic inflammation, and to improve the overall QoL in men with advanced disease. Results will inform future work in this area examining biological markers of prognosis in advanced prostate cancer.Trial registrationClinicaltrials.gov NLM identifier: NCT02453139. Registered on 12 May 2015. This document contains excerpts from the ExPeCT trial protocol Version 1.5, 28 July 2016.

Effects of Aqua-Aerobic Exercise on the Cardiovascular Fitness and Weight Loss among Obese Students

Background: Evidence revealed that aquatic exercises are safer than land-based exercises and it allows increased movement amplitude and energy expenditure for obese, middle-aged, or elderly people, it is important to ascertain the physiological effects of aqua aerobic exercise on health among the obese students. This study aimed to determine the effects of aqua aerobics exercise on cardiovascular fitness (VO2max and resting HR) and weight loss (weight, BMI, and WHR) among obese students.Methods: Fifty healthy obese college students (22.28±1.83 years) with minimum BMI value of 28 kg.m-², voluntarily took part in this study. They have been divided randomly into an exercising group (n=25 and BMI=33.11±5.32kg.m-2) and control group (n=25 and BMI=33.64±3.12kg.m-2). The exercising group participated in an aqua aerobic exercise at 60-75% of maximum HR for 60 minutes, three times per week for 12 weeks. The changes (by pre and post-test) in weight, WHR, resting HR and VO2max were measured for both groups via In Body Scan 370, Polar heart rate monitor and Bleep test, respectively.Results: There was a significant (p≤0.001) improved in weight loss (-8.78±3.61kg), and the changes of BMI (-3.24±1.1kg.m-2), WHR (-0.056±0.035), resting HR (-1.48±1.004 bmp), and VO2max (4.43±2.51 ml.kg-1. min-1) in the exercising group, compared to the control group. The results indicate that the aqua aerobic exercise is an effective way to enhance cardiovascular fitness and weight loss among obese students.Conclusion: Aqua aerobic exercise as a favorable exercise environment for the obese can be advised such a significant intervention strategy for weight loss and improvement in cardiovascular fitness.

Evaluation of Certain Biochemical Parameters of Wrestlers before and after the 20 m Shuttle Run Test

This study was conducted to determine the acute changes after the 20 m shuttle run test in the biochemical parameters and heart rates of wrestlers competing in international competitions on a study population of 21 wrestlers. The mean age of participants was 24.14±2.01years, mean heights 176±0.06 cm, body weight 76.48±14.76 kg, MaxVO2 52.78±3.20 ml/kg/min, and mean BMI 24.44±2.63 kg/m2.20-meter run and sit-up test was applied to measure the MaxVO2 scores of included subjects. Heart rates were monitored using a Polar heart rate monitor before and after the tests. The blood samples that collected at the same time intervals from the vena cephalica were stored in tubes without anticoagulants. The samples were then centrifuged for 10 minutes at 5000 rpm to obtain serum samples, and analyzed. The data obtained were treated using SPSS 15.0 software.This study showed that there was a significant increase (p&lt;0.05) in post-test glucose, HDL-cholesterol and urea concentrations compared to pre-test levels. While the post-test LDL cholesterol concentration was significantly reduced (p&lt;0.05), acute changes in other biochemical parameters were found to be statistically insignificant (p&gt;0.05).It can be concluded that mean glucose, HDL and urea were increased while LDL was reduced after the 20 m shuttle run test in wrestlers.

Ergonomic evaluation of physiological stress of building construction workers associated with manual material handling tasks

Purpose: In India, the cost of manpower is very low; hence Manual Material Handling (MMH) is the cheapest solution. This study aimed to quantify the cardiac strain and postural stress of male building construction workers associated with MMH tasks. Materials and methods: Mean (SD) age (years) and job experience (years) of the workers were 31.0(4.65) and 8.8 (3.23), respectively (n=35). Working peak heart rate was recorded by polar heart rate monitor, posture analysis was done by the Ovako Working Posture Analysis System (OWAS) and the Rapid Entire Body Assessment (REBA) method, body part discomfort was assessed by the Nordic questionnaire, and perceived exertion was evaluated by the Borg scale. Two-tailed unpaired Student’s t test was performed between peak heart rate of workers associated with MMH tasks and upper extremity intensive tasks (n=31). Results: Results revealed that mean peak heart rate of the workers was significantly different (higher) compared with that of the upper extremity intensive workers (p&lt;0.05). This study showed that most of the working postures were hazardous. The magnitude of risk for musculoskeletal disorders (MSD) was much higher as per REBA compared with OWAS. Most of the workers suffered from pain in the head, neck, shoulder, lower back, and arm region. As per the Borg scale, the rate of perceived exertion was ‘hard and heavy’ among most of the workers (68.57%). Conclusions: Postural stress and cardiac strain beyond the safe limit indicates the heavy nature of the job. Load limit optimization, ergonomic lifting technique, and rescheduled work-rest cycle are essential to reducing physiological and perceived work load.

Changes In Heart Rate Variability And Training Load In Elite Football Players

Heart rate variability (HRV) is a popular and accessible monitoring tool utilized ubiquitously in the field to measure autonomic nervous system activity, readiness to train, and training adaptations. Acquisition of this information is essential for coaches, practitioners and athletes in order to effectively monitor positive training adaptations, nonfunctional over-reaching, injury and illness risk. However, longitudinal data assessing HRV changes with respect to training load in elite football is lacking. PURPOSE: To investigate changes in HRV and training load across several weekly training blocks in elite football. METHODS: Six male professional footballers (three defenders, three midfielders) from an English Premier League squad agreed to participate in this study. HRV was assessed with the ithlete application (HRV Fit Ltd, UK) using an Apple iPad2 (Apple Inc, CA), and a Polar T31 heart rate monitor (Polar Electro Ltd, Finland). HRV was calculated for each participant prior to the daily training session. Physical training load was monitored using a Global Positioning System (GPS) to quantify total distance (TD), high speed distance (HSD), training load (TL), impacts, maximum speed (MS), accelerations and decelerations, and energy expenditure (EE). Training sessions were separated into five equal training blocks (weeks 1 - 3, weeks 4 - 6, weeks 7 - 9, weeks 10 - 12 and weeks 13 - 15). RESULTS: There was a significant decrease in TD, HSD, TL, impacts and EE and a significant increase in MS, accelerations and decelerations across the five training blocks (p ≤ 0.03). However, there was no significant change in HRV (p = 0.27). CONCLUSION: The significant change in TL across the 15 week training period, despite no change in HRV may be due to the heterogeneity that exists in elite football players, where some athletes show smaller reductions in HRV in response to training compared to others. Subsequently it is important that individual changes in HRV are interpreted alongside additional monitoring methods (e.g. wellness, training load) to ensure that quantification of training adaptation, readiness to train and overreaching is accurate.

Ergonomic evaluation of physiological stress of building construction workers associated with manual material handling tasks

Purpose: In India, the cost of manpower is very low; hence Manual Material Handling (MMH) is the cheapest solution. This study aimed to quantify the cardiac strain and postural stress of male building construction workers associated with MMH tasks. Materials and methods: Mean (SD) age (years) and job experience (years) of the workers were 31.0(4.65) and 8.8 (3.23), respectively (n=35). Working peak heart rate was recorded by polar heart rate monitor, posture analysis was done by the Ovako Working Posture Analysis System (OWAS) and the Rapid Entire Body Assessment (REBA) method, body part discomfort was assessed by the Nordic questionnaire, and perceived exertion was evaluated by the Borg scale. Two-tailed unpaired Student’s t test was performed between peak heart rate of workers associated with MMH tasks and upper extremity intensive tasks (n=31). Results: Results revealed that mean peak heart rate of the workers was significantly different (higher) compared with that of the upper extremity intensive workers (p&lt;0.05). This study showed that most of the working postures were hazardous. The magnitude of risk for musculoskeletal disorders (MSD) was much higher as per REBA compared with OWAS. Most of the workers suffered from pain in the head, neck, shoulder, lower back, and arm region. As per the Borg scale, the rate of perceived exertion was ‘hard and heavy’ among most of the workers (68.57%). Conclusions: Postural stress and cardiac strain beyond the safe limit indicates the heavy nature of the job. Load limit optimization, ergonomic lifting technique, and rescheduled work-rest cycle are essential to reducing physiological and perceived work load.

Reliability and validity of time domain heart rate variability during daily routine activities – an alternative to the morning orthostatic test?

Summary Study aim: To determine the reliability and validity of a time domain heart rate variability (HRV) index during free-living physical activity (FLPA). Material and methods: Eight white-collar workers participated in this study. RR intervals (time between consecutive R-peaks of the PQRS complex) were recorded using the Polar V800 heart rate (HR) monitor upon awakening and at work on 16 different days. A total of 127 cycles of sitting periods followed by walking breaks were included for consecutive pairwise analysis for reliability. The HR values from the orthostatic test (OT) were compared with the corresponding values at work. Results: The HR values showed high levels of repeatability [the coefficient of variation (CV) during sitting and walking at work was 4.71 and 3.99%, respectively, with a typical error (TE) of 3.73 (3.34-4.25) and 3.65 (3.31-4.09)], but they did not correlate with the corresponding OT HR upon awakening (r = 0.28 for supine vs. sitting and r = 0.05 for standing vs. walking, p &gt; 0.05). The root-mean-square difference of successive normal RR (RMSSD) was revealed not to be repeatable [CV values during sitting and walking were 19.99 and 29.05%, respectively, with a TE of 7.9 (7.15-8.85) and 9.43 (8.53-10.57)]. Conclusions: Analyzing RMSSD from daily routine activities was not reliable, and therefore validity cannot be assumed. RMSSD should therefore be calculated from RR intervals recorded in standardized conditions, such as during the OT upon awakening.

Sensitivity, Specificity and Predictive Value of Heart Rate Variability Indices in Type 1 Diabetes Mellitus.

BackgroundHeart rate variability (HRV) indices may detect autonomic changes with good diagnostic accuracy. Type diabetes mellitus (DM) individuals may have changes in autonomic modulation; however, studies of this nature in this population are still scarce.ObjectiveTo compare HRV indices between and assess their prognostic value by measurements of sensitivity, specificity and predictive values in young individuals with type 1 DM and healthy volunteers.MethodsIn this cross-sectional study, physical and clinical assessment was performed in 39 young patients with type 1 DM and 43 young healthy controls. For HRV analysis, beat-to-beat heart rate variability was measured in dorsal decubitus, using a Polar S810i heart rate monitor, for 30 minutes. The following indices were calculated: SDNN, RMSSD, PNN50, TINN, RRTri, LF ms2, HF ms2, LF un, HF un, LF/HF, SD1, SD2, SD1/SD2, and ApEn.ResultsType 1 DM subjects showed a decrease in sympathetic and parasympathetic activities, and overall variability of autonomic nervous system. The RMSSD, SDNN, PNN50, LF ms2, HF ms2, RRTri, SD1 and SD2 indices showed greater diagnostic accuracy in discriminating diabetic from healthy individuals.ConclusionType 1 DM individuals have changes in autonomic modulation. The SDNN, RMSSD, PNN50, RRtri, LF ms2, HF ms2, SD1 and SD2 indices may be alternative tools to discriminate individuals with type 1 DM.

Efeito da acupuntura nas respostas de estresse em equinos atletas submetidos a reprise de adestramento

Horses have a natural predisposition for sport, however, their use in competitions can result in stress-related problems that impair their sporting performance and especially their health. Thus, the use of strategies that can prevent or minimize the deleterious effects of stress is essential. In this sense, acupuncture is an ancient technique of Traditional Chinese Medicine that has been used in the treatment and prevention of stress-related diseases. Therefore, we evaluated whether acupuncture can alter stress responses in horses submitted to a dressage test. Six Brasileiro de Hipismo horses, aged between 6-8 years old, used for dressage training, from Army Riding School, Rio de Janeiro, Brazil were used. The effect of acupuncture at points GV1, HT7, GV20, and B52 immediately before to the dressage was evaluated through analysis of test performance, serum cortisol and heart rate variability (HRV). Polar Equine ™ heart rate monitor was used for HRV analysis and blood samples were collected before and 30 minutes after the end of the dressage. The performance was judged by official judges and by the riders. Acupuncture significantly reduced the LF / HF ratio (p < 0,0001), an index that indicates the sympathovagal balance suggesting that acupuncture can reduce the cardiac autonomic response in stressful situations. However, acupuncture had no effect on heart rate, cortisol levels and performance assessed by judges and riders. Our results suggest that acupuncture may reduce some stress responses in horse athletes submitted to dressage and that this effect can be related to its potentiating action of vagal activity

Examining The Validity Of Fitbit Charge HR For Measuring Heart Rate In Free-living Conditions

Optical blood flow sensors (i.e. photoplethysmographic techniques) have recently been utilized in wearable activity trackers. The Fitbit Charge HRTM (FBHR) is one of the widely recognized wearable activity trackers that utilizes Fitbit’s proprietary PurePulse optical heart rate (HR) technology to automatically measure wrist-based HR. Despite its increasing popularity, however, no study to date has addressed the validity of FBHR for measuring HR in free-living conditions. PURPOSE: The purpose of this study was to examine the validity of FBHR for measuring HR using a chest strap Polar HR monitor (PHR) as a reference measure in free-living conditions. METHODS: Ten healthy college students (8 males; mean age = 26.5 ± 5.4 years; mean body mass index (BMI) = 24.5 ± 3.23 kg·m2) participated in the study. The participants were asked to perform normal daily activities for 8 hours in a day while wearing the PHR (model RS400) on their chest and two FBHRs on their dominant and non-dominant wrists, respectively. HR was recorded every minute and the minute-by-minute HR data from each monitor were synchronized by time of day. Pearson correlation was used to examine the linearity of average beats-per-minute (bpm) estimated from FBHRs with respect to the PHR. Mean differences in average bpm between the monitors were examined by a general linear model for repeated measures. Lastly, mean absolute percentage error (MAPE) of minute-by-minute bpm estimated from the FBHRs were calculated against the PHR. RESULTS: Average HRs (mean ± SD) for PHR, FBHR non-dominant, and FBHR dominant were 75.6 ± 18.5 bpm, 72.8 ± 16.7 bpm, and 73.9 ± 17.06 bpm, respectively. Pearson correlation coefficients (r) between the PHR and FBHR non-dominant and dominant were r=.805 and r=.793, respectively. MAPE were 9.17 ± 10.9% for FBHR non-dominant and 9.71 ± 12.4% for FBHR HR dominant. ANOVA and post-hoc analyses with Bonferroni revealed significant differences in estimating HR from FBHR non-dominant wrist (p=.001) and FBHR dominant wrist (p=.001) compared to PHR monitor. CONCLUSION: The results indicated that the wrist-oriented Fitbit Charge HRTM device does not provide an accurate measurement of HR during free-living condition in this study. However, further research is needed to validate these monitors with a larger sample with different population groups.

Activation Of Lower Limb Deep Muscles During Deep Squats On Different Unstable Surfaces

Although there are many studies about the effect of unstable conditions on surface muscles during deep squats, a key human movement, the conclusions were not consistent, e.g., while some studies showed that unstable conditions decreased force generation and the muscular activities increased with the level of instability, others concluded that there were not significant changes in muscle patterns among unstable surfaces. PURPOSE: To evaluate the effect of unstable conditions on both deep and surface muscles activation during deep squat posture. METHODS: Eighteen healthy males (22.3±1.8 years, height: 173±4 cm, mass: 67.4±5.8 kg) volunteered for the experiment. One repetition maximum (1RM) tests (69.5±7.6 kg) were performed for squats on stable surface. The sEMG of the tibialis anterior (TA) and rectus femoris (RF) were collected by a Trigno EMG system when holding the deep squat posture (thigh and calf at an 80 degree angle ) for 5s on Balance Disc (BD, unstable) and on ground (stable) with 30%RM. The thickness of TA, RF, hallucis longus (HL) and shares muscle (SM) were measured by APLIO Doppler 400 at the same time. A polar heart rate monitor was used to ensure participants’ heart rates were under 100 beats/minute.Paired t-test and effect size (ES, Cohen’s d) were calculated to evaluate the difference between stable and unstable conditions. RESULTS: 1. sEMG and thickness of muscle responded similarly during deep squating. 2. Significant difference was observed for TA, HL, and SM between stable and unstable surfaces (Table 1).Table 1: The difference of muscle activation between unstable and stable conditionsCONCLUSIONS: Compared with the stable condition, deep muscle activation increased to adapt to the unstable condition. Study was supported by Independent scientific research plan of Ministry of Education (20121088023)

Heart Rate Variability And Autonomic Activity In A Nonfunctional Overreached Professional Soccer Player

PURPOSE: In order to investigate nonfunctional overreaching (NFOR) related adaptations in the autonomic nervous system, heart rate variability (HRV) was examined in a professional soccer player (age: 28.6 years; weight: 77.4 kg; height: 177.1 cm; adiposity: 12.1 %; VO2 Max 57 ml/kg/min) who showed reduced performance in competitions, frequent muscular fatigue during some training sessions (same period), and finally getting upper respiratory tract infection (URTI). METHODS: HRV analysis was performed once a week during three periods of competitive season: initial, NFOR state and post-recovery (5-month follow-up). Short-term recordings (5 minutes) were made with a Polar RS800CX heart rate monitor in two positions: supine (S) and 90° head-up tilt (T), immediately after awakening (match day morning). Root mean square of successive differences (RMSSD) and power spectral density were measured. LF/HF ratios in S and T positions were calculated and mean resting heart rate (RHR) was also analyzed. Seven players from the same team and with normal performances during the season were used as a control group (age: 26.6 ± 3.1 years; weight: 73.2 ± 6 kg; height: 176.7 ± 10 cm; adiposity: 12.9 ± 1.6 %; VO2 Max 55.7 ± 1.8 ml/kg/min). The typical 95% confidence interval (CI) in every HRV parameter was calculated in this group. To be diagnosed as NFOR, the subject (case) had to reveal a 95% difference with respect to the lower or upper CI limit reported in the control group. Values are expressed as mean ± SD. RESULTS: LF/HF ratio decreased progressively throughout the competitive period in S and it was substantially different in comparison with control subjects in T during the NFOR state (0.26 ± 0.62 vs. 2.03 ± 1.25). Relevant differences of RMSSD in S (107.6 ± 20.2 vs. 74.6 ± 23.8 ms) and T (140.3 ± 15.3 vs. 61.6 ± 21.6 ms) were found in NFOR. According to this phenomenon, RHR was lower than the control group in S (45.3 ± 1.7 vs. 55.7 ± 6.5 bpm) and T (48.2 ± 2.4 vs. 59.8 ± 9.1 bpm) and returned to baseline after recovery. CONCLUSIONS: The results suggest a sympathovagal imbalance with extensive parasympathetic modulation in a player identified as overreached. Relevant increase of RMSSD and decrease of LF/HF ratio reflect alterations in autonomic function, which should be taken into account when complete recovery is essential to prevent overtraining syndrome.

Effects of Performance Enhancing Clothing on Cardiovascular Endurance

Performance enhancing garments have attempted to improve cardiovascular endurance by increasing venous return via compression technology or to improve thermoregulation to increase endurance by decreasing thermal stress. Recently developed proprietary clothing technology claims to increase cardiovascular endurance by altering the electromagnetic microclimate next to the skin, possibly increasing vasodilation. PURPOSE: To compare cardiovascular endurance using the Chester Step Test in novel technology clothing using a randomized double blind trial with deception. METHODS: 15 healthy adult athletes (9 females, 6 males 29 +/-5 yrs; low to high intensity exerciser 2-6 x week) gave informed consent to participate in this IRB-approved protocol. The athletes completed 4 exercise sessions over 9 days, performing the Chester Step Test with Polar heart rate monitor to record participants’ heart rates on a iPad. The athlete stepped onto and off a 30.5 cm box at 60 Hz using a metronome. Every two minutes heart rate and Rating of Perceived Exertion (RPE) using the Borg scale were checked and stepping rate was increased by 20 Hz. The test was stopped once the athlete reached 80% heart rate maximum, the athlete was unable to keep the set pace, or intensity was moderately hard (>=14) using RPE. The athletes wore t-shirts and shorts that were identical in look and feel except for the technology treatment (enhanced) or not (control). Conditions were tested in random order: True Positive (athlete told they were in the enhanced clothing and were in the enhanced clothing; True Negative (athlete told they were in control clothing and were in control clothing; False Positive (athlete told they were enhanced clothing but were not); and False Negative (athlete told they were not in enhanced clothing but were). The endurance times were compared using a repeated measures ANOVA. RESULTS: There was no statistically significant difference in the endurance test duration in any of the conditions (main effect P = 0.53). True Positive 361.3 ± 106.4 sec; True Negative 362.2 ± 94.2 sec; False Positive 365.5 ± 85.5; and False Negative 332.1 ± 107.0 sec. CONCLUSION: It appears from these data that the enhanced technology clothing did not improve endurance exercise duration, nor did the awareness of the enhanced clothing improve endurance exercise duration.

Effects of elevation change on mental stress in high-voltage transmission tower construction workers

High-voltage transmission tower construction is a high-risk operation due to the construction site locations, extreme climatic factors, elevated working surfaces, and narrow working space. To comprehensively enhance our understanding of the psychophysiological phenomena of workers in extremely high tower constructions, we carried out a series of field experiments to test and compare three working surface heights in terms of frequency-domain heart rate variability (HRV) measurements. Twelve experienced male workers participated in this experiment. The dependent variables, namely, heart rate (HR), normalized low-frequency power (nLF), normalized high-frequency power (nHF), and LF-to-HF power ratio (LF/HF), were measured with the Polar RS800CX heart rate monitor. The experimental results indicated that the task workload was similar between working surface heights. Tower construction workers perceived an increased level of mental stress as working surface height increased.

Association of cardiac autonomic modulation with physical and clinical features of young people with type 1 diabetes.

The objective of this study was to verify possible associations between heart rate variability indices and physical activity, body composition, and metabolic and cardiovascular parameters in individuals with type 1 diabetes. A total of 39 young patients with type 1 diabetes were included. Body composition, physical activity, cardiovascular parameters, and metabolic parameters were assessed. For the heart rate variability analysis, heart rate was recorded beat-by-beat using a Polar S810i heart rate monitor for 30 minutes, with the volunteers in the supine position; subsequently, the following indices were considered: standard deviation of all normal RR intervals; root-mean square of differences between adjacent normal RR intervals in a time interval; percentage of adjacent RR intervals with a difference of duration >50 ms; high frequency component in milliseconds squared; high frequency component in normalised units; standard deviation of the instantaneous variability beat-to-beat; and standard deviation of the long-term variability. The association between the heart rate variability indices and independent variables was verified through linear regression in unadjusted and adjusted models (considering gender and age). The statistical significance was set at 5% and the confidence interval at 95%. High values of at-rest heart rate were associated with reduced parasympathetic activity and global heart rate variability, and higher values of waist-to-hip ratio were related to lower parasympathetic activity, independent of age or gender. For young patients with type 1 diabetes, increases in at-rest heart rate values are associated with reduced parasympathetic activity and global heart rate variability, whereas higher waist-to-hip ratio values are related to lower parasympathetic activity, both independent of age and gender.

Heat stress and its impacts on occupational health and performance

Workplace heat stress is a well-known occupational health hazard, and climate change characterized by the increased frequency and intensity of extreme heat events has made risks more severe and widespread. Heat stress is prevalent in numerous industrial and commercial occupational settings, either outdoors or indoors. Operations that involve high environmental heat, physically demanding activities or impermeable protective clothing have a high potential for incurring heat stress among exposed workers. Workplaces with such conditions may include firefighting, iron and steel manufacturing, mining, glass factories and food canneries. Outdoor tasks performed in hot weather and under direct exposure to sunlight, such as construction, agriculture, oil and gas well operations, and outdoor horticulture and cleaning, are also likely to induce heat stress to employees. This editorial paper highlights the current progress and needs for research on heat stress and of its impacts on occupational health and performance. Heat stress causes physiological and psychological discomforts, deteriorates performance and productivity, increases incident rates and even threatens survival. Increased thermoregulatory, cardiovascular and perceptual strains on the body promote confusion, irritability and other emotional stress, which may cause workers to become distracted from tasks or ignore safety procedures. Understanding the effects of heat stress and implementing appropriate intervention strategies to relieve the harmful impacts of heat stress has been the focus of a significant amount of research. Studies of this nature require a multi-disciplinary approach involving physiology, management and technology. The effects of heat stress can be described by physiological and psychological responses. Management of heat stress utilizes a set of framework, principles, processes and measures to prevent injuries, accidents and other adverse consequences. Technology in terms of techniques, tools, systems and machineries has been adopted as an effective means to protect workers from the hazardous effects of heat stress. Heat stress could be a result from a combination of factors, including environmental conditions, metabolic heat and thermal effects of clothing ensemble. Heat strain is the physiological response of a person in dissipating heat stress. The international standard, ISO 9886:2004 specifies measurements of body core temperature, heart rate, skin temperature and loss of body mass through sweating for evaluation of body heat strain. The upper limits of these physiological parameters have been prescribed by some regulatory organizations for monitoring of workers’ safety in heat stress occupational environments. So far a number of devices such as Ingestible Core Body Thermometer Pill and Polar Heart Rate Monitor have been used for measurement and monitoring of these physiological parameters. However, application of these devices is limited and inconvenient because they are costly and may disturb workers’ normal activities. The physiological strain experienced by a person can be estimated by the heat stress factors and is evaluated by a single index. A heat stress index is a single value that integrates the effects of the six basic parameters (i.e. ambient temperature, relative humidity, radiant temperature, air velocity, metabolic rate and clothing properties) in any human thermal environment such that its value could vary with the thermal strain experienced by an individual. Measurement of wet bulb globe temperature is by far the most widely used and accepted empirical index for managing occupational heat stress; and is recommended as a heat stress standard. The heat stress standard is calculated using the recordings of wet bulb temperature, globe temperature and dry bulb temperature. However, wet bulb globe temperature measurements are insensitive to the cooling effect due to wind velocity and are incapable of measuring the effect of workers’ metabolic rates.