Effect of acute high-intensity interval exercise on a mouse model of doxorubicin-induced cardiotoxicity: a pilot study

BACKGROUND

It is unknown whether high-intensity interval exercise (HIIE) may potentiate or attenuate the cardiotoxic effect of chemotherapy agents such as doxorubicin (DOX) when performed shortly after treatment. The study aimed to investigate the effect of acute HIIE on cardiac function and structure performed either 1, 2 or 3 days after DOX injection in an animal model.

METHODS

Female C57bl/6 mice (n = 28), 70 days old, received a bolus 20 mg/kg intravenous tail vein DOX injection. Three exercise groups performed 1 HIIE session (16 sets of 1 min at 85-90% of peak running speed) at 1 (n = 7), 2 (n = 7), and 3 days (n = 8) following the DOX injection. A sedentary (SED) group of mice (n = 6) did not exercise. Animals underwent echocardiography under light anesthesia (isoflurane 0.5-1%) before and 7 days after the DOX injection. Animals were sacrificed on day 9 and hearts were collected for morphometric and histological analysis.

RESULTS

Animals exercising on day 3 had the smallest pre-post reduction in left ventricular fractional shortening (LVFS) (MΔ= -1.7 ± 3.3; p = 0.406) and the SED group had the largest reduction (MΔ=-6.8 ± 7.5; p = 0.009). After reclassification of animals according to their exercise compliance (performing > 8/16 of high-intensity bouts), LVFS in compliant mice was unchanged over time (LVFS MΔ= -1.3 ± 5.6; p = 0.396) while non-compliant animals had a LVFS reduction similar to sedentary animals. There were no significant differences in myocardial histology between groups.

CONCLUSIONS

In this pilot murine study, one single HIIE session did not exacerbate acute doxorubicin-induced cardiotoxicity. The timing of the HIIE session following DOX injection and the level of compliance to exercise could influence the negative impact of DOX on cardiac function.

Cranberry supplementation improves physiological markers of performance in trained runners

PURPOSE

Cranberries have the highest polyphenol and antioxidant capacity among fruits and vegetables and may protect against exercise-induced free radical production, consequently improving performance. This study aimed to investigate the effect of polyphenol-rich cranberry extract (CE) on time-trial performance and lactate response following exercise.

METHODS

A total of 14 trained runners were tested at i) baseline, ii) 2 h following an acute CE dose (0.7 g/kg of body mass), and iii) 4 weeks after daily supplement consumption (0.3 g/kg of body mass). At each time point, runners performed a 1500-m race followed by a 400-m race where the live vastus lateralis oxygenation changes were determined by near-infrared spectroscopy and blood lactate was measured at rest and 1 and 3 min after each trial. The Shapiro-Wilk test and repeated-measures analysis of variance were used to establish significance (P <0.05).

RESULTS

Cranberry supplementation over 28 d improved aerobic performance during the 1500-m time trial, whereas the acute dose had no effect. More specifically, muscle reoxygenation rates were significantly faster after 28 d compared to baseline (P = 0.04; η² = 0.29), and a trend towards slower deoxygenation rate was observed (P = 0.13; η² = 0.20). Chronic CE consumption also buffered the post-exercise lactate response for the 400-m race (P = 0.01; η² = 0.27), while no effects were seen for the longer race.

CONCLUSION

Our results suggest that cranberry supplementation may have ergogenic effects, as it improves physiological markers of performance during short- and long-distance running.

Body Composition and Maximal Strength of Powerlifters: A Descriptive Quantitative and Longitudinal Study

The purpose of this study was to present the relationships between maximal strength and body composition and to conduct yearly follow-ups presenting the chronic effects of maximal strength training on body composition. Thirty-four (age = 28.8 ± 8.7 yrs) classic powerlifters (M = 21; F = 13) completed at least one Dual-Energy X-Ray Absorptiometry (DXA) 43.97 ± 23.93 days after a sanctioned international powerlifting federation affiliate competition (Squat + Bench Press + Deadlift = Total (kg)). In addition, thirteen subjects (n = 13) completed at least one yearly follow up. Paired sample T-Tests and simple linear regressions were performed to determine significant effects on body composition and maximal strength measures. Prediction formulas were obtained as follows: Bone Mineral Content (BMC) (g) = 3.39 * Total (kg) + 1494.78 (r = 0.84; p < 0.000; SEE = 348.05); Bone Mineral Density (BMD) (g/cm3) = 0.000390 * Total (kg) + 1.115 (r = 0.71; p < 0.000; SEE = 0.062); Total (kg) = 10.84 * Lean Body Weight (LBW) (kg) - 154.89 (r = 0.90; p < 0.000; SEE = 70.27); Total (kg) = 22.74 * Relative LBW (kg/m) - 306.66 (r = 0.92; p < 0.000; SEE = 64.07). Significant differences were observed in BMD (+1.57 ± 1.55%; p = 0.018; ES = 0.22), between measures one and two (333.7 ± 36.3 days apart) as well as LBW (-2.95 ± 3.82%; p = 0.049; ES = 0.16), and Body Fat Percentage (+2.59%; p = 0.029; ES = 0.20) between measures two and three (336 ± 13.3 days apart). Thus, maximal strength can be used to predict BMC and BMD, while LBW can be used to predict maximal strength. As well, consistent powerlifting practice can increase BMD in adults.

Wrist-worn devices for the measurement of heart rate and energy expenditure: A validation study for the Apple Watch 6, Polar Vantage V and Fitbit Sense

The purpose of this study was to investigate the accuracy of 3 recently released wrist-worn devices (Apple Watch 6, Polar Vantage V and Fitbit Sense) for heart rate and energy expenditure during various activities. The study population consisted of 60 young healthy individuals (30 men and 30 women; age: 24.9 ± 3.0 years, BMI: 23.1 ± 2.7 kg/m2). Heart rate and energy expenditure were measured using the Polar H10 and Metamax 3B, respectively (reference measures) as well as with the 3 wrist-worn devices during 5 different activities (sitting, walking, running, resistance exercises and cycling). The Apple Watch 6 displayed the highest level of accuracy for heart rate measurement with a coefficient of variation (CV) (%) of less than 5% for all 5 activities, whereas the Polar Vantage V and the Fitbit Sense presented various degrees of accuracy (from high to poor accuracy) dependent on the activity (CVs between 2.44-8.80% and 4.14-10.76%, respectively). As for energy expenditure, all 3 devices displayed poor accuracy for all 5 physical activities (CVs between 14.68-24.85% for Apple Watch 6, 16.54-25.78% for Polar Vantage V and 13.44-29.66% for Fitbit Sense). Results of the present study indicate that the Apple Watch 6 was the most accurate for measuring heart rate across all 5 activities, whereas variable levels of accuracy for heart rate measurement for the Polar Vantage V and the Fitbit Sense were observed depending on the activity. As for energy expenditure, all 3 devices showed poor accuracy during all activities.Highlights The Apple Watch 6 was the most accurate for measuring heart rate, whereas the Polar Vantage V and Fitbit Sense showed variable results dependent on the activityThe Apple Watch 6, Polar Vantage V and Fitbit Sense showed poor accuracy for energy expenditure during 5 different physical activitiesHealthcare care professionals, athletes/coaches and the general population may want to proceed with caution on the clinical utility of energy expenditure of these devices during the implementation of an exercise training or nutritional programme.

Secular trends of cardiorespiratory fitness in children and adolescents over a 35-year period: Chronicle of a predicted foretold

Background

In the context of concerns regarding the cardiorespiratory fitness (CRF) of youth populations, the aims of this study were: (1) to update reference values for the VO₂max for school-aged Canadians and (2) to document secular trends in CRF after a 35-year interval.

Methods

Between September 2014 and April 2017, the CRF of 3725 students (53.2% boys; 6.0 to 17.9 yrs) was determined using the 20-m shuttle run test. The sample was collected in 36 different schools from six cities of Québec (Canada).

Results

Median values of VO₂max decreased with age in both sexes (p ≤ 0.05). By the age of 10, more than 20% of boys showed VO₂max values below the recommended value (42 ml·kg^-1·min^-1). At the age of 17, that proportion reached 56.8%. A similar proportion of 12 yrs girls (20%) were under the recommended minimal value (37 ml·kg^-1·min^-1) and that value reached 69.9% at the age of 17. Compared to 1982, the VO₂max at age 17 has declined by 18% for boys and 12% for girls. The situation is worse in terms of functional capacity (number of stages completed) with an overall decrease of more than 30%.

Conclusion

This study demonstrates that, compared to data obtained using the same methodology 35 years ago, the CRF and functional capacity of children and adolescents has declined to levels that should raise concerns from a public health perspective. Thus, the development of strategies to promote a physically active lifestyle in youth is more relevant than ever.

Static Postural Control Deficits in Adults with Myotonic Dystrophy Type 1, Steinert Disease

BACKGROUND

Myotonic dystrophy type 1 (DM1) is characterized by progressive and predominantly distal muscle atrophy and myotonia. Gait and balance impairments, resulting in falls, are frequently reported in this population. However, the extent to which individuals with DM1 rely more on a specific sensory system for balance than asymptomatic individuals (AI) is unknown.

OBJECTIVE

Evaluate postural control performance in individuals with DM1 and its dependence on vision compared to AI.

METHODS

20 participants with DM1, divided into two groups based on their diagnosis, i.e. adult and congenital phenotype, and 12 AI participants were recruited. Quiet standing postural control was assessed in two visual conditions: eyes-open and eyes-closed. The outcomes measures were center of pressure (CoP) mean velocity, CoP range of displacement in anteroposterior and mediolateral axis, and the 95% confidence ellipse's surface. Friedman and Kruskal-Wallis analysis of variance were used to compare outcomes between conditions and groups, respectively.

RESULTS

Significant group effect and condition effect were observed on postural control performance. No significant difference was observed between the two DM1 groups. The significant differences observed between the AI group and the two DM1 groups in the eyes-open condition were also observed in the eyes-closed condition.

CONCLUSIONS

The result revealed poorer postural control performance in people with DM1 compared to AI. The DM1 group also showed similar decrease in performance than AI in eyes-closed condition, suggesting no excessive visual dependency.

Remote Ischemic Preconditioning Does Not Improve the Six Minutes Walk Test Performance in Chronic Heart Failure Patients: a Randomised Pilot Trial

Cycles of ischemia and reperfusion induced with a pressure cuff on a skeletal muscle, also know as remote ischemic preconditioning (RIPC), appears to improve performance in different time-trial events in healthy individuals. Our primary goal was to assess the effect of RIPC in heart failure (HF) patients' functional capacity using the six-minute walk test (6MWT). A randomized crossover design comparing RIPC (4 × five-minutes of upper arm ischemia) to the SHAM procedure was done in 15 patients prior to a 6MWT. The primary outcome measure was the total distance walked in a standardized 6MWT (20m corridor). Metabolic and hemodynamic responses were measured using gas exchange analysis with a portable metabolic analyzer and peripheral skeletal muscle oxygen saturation (smO₂) with near-infrared spectroscopy. The total distance travelled during 6MWT was not significantly different between the RIPC (347 ± 63 m) and the SHAM procedure (352 ± 65 m; p = 0.514). Relative oxygen uptake did not change when comparing interventions: 10.26 ± 2.01 ml/kg/min vs 10.69 ± 2.51 ml/kg/min (RIPC vs SHAM, respectively, p = 0.278). As well, no significant differences were observed for heart rate, respiratory exchange ratio, smO₂, and ventilation. Even though HF patients tolerated well the RIPC intervention, it did not provide any significant improvement in functional capacity and other physiological parameters in our sample of patients.

Ice Hockey Goaltender Physiology Profile and Physical Testing: A Systematic Review and Meta-Analysis

This review aims to 1) be the first systematic review and meta-analysis of the literature examining the physiology and assessment of goaltenders, and 2) present a physiological profile of ice-hockey goaltenders. It will 1) highlight physiological differences between goaltenders and players at other positions, 2) determine strengths and weaknesses of ice hockey goaltenders, and 3) offer possible guidelines for strength and conditioning coaches. Six electronic databases were systematically searched in October 2019 using the PRISMA model. A total of twelve scientific articles published in peer-reviewed journals were included. Professional male (PM) goaltenders had the following profile for age (A) 26.8 ± 2.5 years, body weight (BW) 85.64 ± 3.79 kg, height (H) 184.38 ± 2.79 cm, body fat % (BF%) 11.9 ± 2.22, VO₂max 49.9 ± 4.45 ml/kg/min, anaerobic power (AP) 12.78 ± 1.63 W/kg, and combined hand grip strength (GS) 120.7 ± 15 kg. Amateur male (AM) goaltenders presented the following: A: 18.2 ± 0.75, BW: 83.85 ± 4.51, H: 184.96 ± 2.06, BF%: 10.51 ± 1.61, VO₂max: 55.73 ± 4.57, AP: 10.9 ± 1.2 and GS: 109.08 ± 14.06. Amateur female (AF) goaltenders presented the following: A: 21.04 ± 1.84, BW: 63.4 ± 5.14, H: 164.86 ± 5.73, BF%: 22.12 ± 2.27 and VO₂max: 42.84 ± 3.59. Overall, PM goaltenders are heavier, have a higher BF%, and exhibit greater GS and abdominal muscular endurance than AM, while AM goaltenders are heavier, taller, leaner, and can generate greater lower-body muscular power than AF goaltenders. In the current literature, there were a small number of studies on women players and a lack of distinction between player position in reported results. Specific physiological assessments during NHL Combines should be developed for goaltenders in accordance with their specific positional demands.

Unclear outcomes of heart rate variability following a concussion: a systematic review

PURPOSE

: To systematically regroup articles that were published since the latest systematic search, but with specific inclusion criteria to help comparison that will offer a focused presentation of methods and results. This will offer a full overview of HRV's behavior at rest and during exercise in adults post-concussion.

METHODS

: The systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method. A computer-based systematic search was conducted in December 2019 through the Pubmed, Scopus and SPORTDiscus databases. A manual search was performed through the reference list of all articles retained. The reliability of the systematic search was assured by having the article selection process entirely repeated by a second author.

RESULTS

: The systematic search yielded a total of 15 articles to be further analyzed. Results show impairment of HRV during exercise for individuals with concussion, heterogenous studies with lack of control over confounding factors and only less than half of the results showing a significant difference between individuals with concussion and controls.

CONCLUSION

: Further research should try standardizing HRV measurement protocols that control confounding factors to allow easier comparison between studies and allows the possibility for an eventual meta-analysis.

Maximal Oxygen Consumption Requirements in Professional North American Ice Hockey

ABSTRACT

Ferland, P-M, Marcotte-L'Heureux, V, Roy, P, Carey, V, Charron, J, Lagrange, S, Leone, M, and Comtois, AS. Maximal oxygen consumption requirements in professional North American ice hockey. J Strength Cond Res 35(4): 1586-1592, 2021-This study was designed to measure preseason on-ice relative V̇o2max of professional ice-hockey players (n = 101 National Hockey League [NHL], 42 American Hockey League [AHL], 4 East Coast Hockey League [ECHL], and 15 Canadian Hockey League [CHL]) throughout 17 years and compare it between generations, league level, and position, and to verify if it was related to season and NHL career statistics. Relative V̇o2max was measured on ice with a portable metabolic analyzer (K4b2, Cosmed, Rome) with full hockey equipment, except for the helmet with either the Skating Multistage Aerobic Test or the 30-15 intermittent ice test tests. Relative V̇o2max results from both tests were compared between players of the same generation with an independent-samples T-test and were not significantly different. A one-way analysis of variance and post hoc pairwise tests were performed to detect significant differences between groups. Pearson correlations (two-tailed) were also performed between selected variables. All statistical significance was set at p < 0.05. Results show that there are no significant differences for relative V̇o2max between generations (2001-2003 vs. 2006 vs. 2015-2017), league level (NHL vs. AHL vs. ECHL vs. CHL), and position (winger, center, and defense), other than the ECHL being lower. There are also no significant relationships between V̇o2max values and hockey season and NHL career statistics. Thus, the results show that there is a minimal relative V̇o2max requirement to play North American ice hockey at the elite level (55.9 ± 5.2 ml·kg-1·min-1; n = 162). Future research should be directed toward comparing V̇o2max of elite and amateur ice-hockey players to confirm the minimal relative V̇o2max requirement to play North American ice hockey at the elite level.

Psychological Status During and After the Preparation of a Long-distance Triathlon Event in Amateur Athletes

Preparation for an endurance event among amateur athletes requires a major commitment on their part. Knowing amateur athletes' psychological characteristics during a training period should be a priority for coaches and athletes. The aim of our longitudinal study was to characterize the psychological profile of amateur athletes over a training period of six months prior to and after a long-distance triathlon. Thirty-two amateur athletes (13 females; 19 males; 1.5±1.3 years of experience) were recruited for this observational study. All participants (39±9.9 years old; weighs 73±12.9 kg; measure 172±10.2 cm) underwent a physical fitness assessment pre- and post 6-months of training, a monthly psychological questionnaire battery assessing mood, positive and negative affect, passion and motivation and, for some participants (n=5), an interview post event. Positive emotions increased until the sixth month, from 38.1±22.0 to 54.3±7.2 (Z=3.49, p<0.001, r=0.80). Participants were more harmonious (29.0±3.0) than obsessive (13.0±1.0) with their triathlon's passion (Z=4.91, p<0.001, r=0.85). Participants felt a high level of intrinsic motivation (15.9±1.76) and a low level of external motivation (4.9±1.08) about their triathlon training (p<0.05). The vigor score is the only sub scale that significantly changed from the 1^st to the 6^th month of training, and ranged between 21.4±10.6 and 28.1±4.1 (Z=2.0, p=0.046, r=0.46). This longitudinal observational study is the first to have explored athletes' psychological and emotional parameters over a training period of six months prior to a long-distance triathlon event and one month after. Thus, specific interventions and mental training can be structured around these important milestones.

Relationships Between Anthropometry and Maximal Strength in Male Classic Powerlifters

Several studies have determined the influence of physical characteristics on strength. The present quantified the relationships between anthropometry and maximal strength. Male classic powerlifters (n=59) were measured before a championship. Two-tailed Pearson correlation analysis was used. Powerlifters that presented higher relative maximal strength (RMS) in the squat and bench generally had higher body weight (BW), body mass index (BMI), torso circumference (C), waist C/height, torso C/height (r=0.26 to 0.49, p<0.05), and smaller lower leg length (L)/height and forearm L/torso C (r=-0.31 to -0.45, p<0.05) ratios. Powerlifters with a higher % of their deadlift on their total generally presented a smaller BW, BMI, body fat percentage (BF%), waist and torso C, trunk L, waist C/height, torso C/height, trunk L/height, waist C/hip C, thigh L/lower leg L, trunk L/thigh L ratios (r=-0.26 to -0.49, p<0.05) and higher lower leg L, lower leg L/height, reach/height, and forearm L/torso C ratios (r=0.32 to 0.51, p<0.05). Stepwise regressions revealed that a bigger torso positively predicted absolute maximal strength (AMS) in the squat (β=0.41, p=0.04), the bench (β=0.77, p<0.01), the deadlift (β=0.88, p<0.01) and the total (β=0.89, p<0.01), that a higher torso C/height ratio positively predicted RMS in the squat(β=0.48, p<0.01), the bench (β=-0.87, p<0.01) and the total (β=0.66, p<0.01), and that reach/height positively predicted RMS in the deadlift (β=0.37, p<0.01) and it's % on the total (β=0.31, p<0.01), but negatively predicted RMS in the bench (β=-0.25, p=0.02) and its % on the total (β=-0.24, p=0.04) As all of the stronger correlations came from AMS, powerlifters should focus on increasing AMS (weight lifted) instead of RMS (Wilks pts).

Efficiency of the Wilks and IPF Formulas at Comparing Maximal Strength Regardless of Bodyweight through Analysis of the Open Powerlifting Database

The purpose of this study was to measure the efficiency of the Wilks and International Powerlifting Federation (IPF) Formulas at comparing powerlifting performance (total) between weight classes of the same sex (men and women) and division (classic and equipped) in order to determine the champion of champions. The Open Powerlifting database was downloaded (June 21st, 2019), filtered (Python) and analyzed (IBM SPSS). Single factor ANOVA revealed that the total (kg) was able to compare 3 out of the 98 weight class comparison possibilities (3.1%), the total ratio was able to compare 5 of the 98 weight class comparison possibilities (5.1%), the Wilks Formula was able to compare 53 of the 98 weight class comparison possibilities (54.1%) and that the IPF formula was able to compare 51 of the 98 weight class comparison possibilities (52%). Making the Wilks slightly more efficient than the IPF Formula (54.1% > 52%) at determining the champion of champions. Results also show that the IPF Formula is more efficient at comparing women's weight classes and that the Wilks Formula is more efficient at comparing men's weight classes, for both divisions. Results could not validate the IPF's decision to replace the Wilks by the IPF Formula. Subjects' performances (kg, ratio, % of the event on the total, Wilks and IPF points) presented for each weight class per sex and division coming from a total of 26,472 open powerlifters could be utilized by practitioners. Further research should be directed towards updating the constants of both formulas.

Physiological Responses to Repeated Running Sprint Ability Tests: A Systematic Review

The purpose of this study was to review acute physiological responses induced by repeated running sprint ability (RRSA) tests that could serve as references for practitioners utilising repeated sprints as a performance measure with athletes. This research was conducted following the PRISMA methodology. The systematic search was conducted in November 2019 and yielded 26 different scientific articles. Only peer-reviewed full-text article were included as abstracts are too short to allow proper explanation of the RRSAT methodology that was employed. According to the present literature, practitioners should use the following assessments: the 6×40m RRSA protocol with one Change of Direction (COD) (20+20 m with a 180° COD) and 25s of passive recovery between sprints with soccer players; the Intensive Repeated Sprint Ability (IRSA) test with men basketball players; the Futsal Intermittent Endurance Test (FIET) with futsal players; the Repeated Shuttle Sprint Test (RSST) with men handball players; and the Multiple Repeated Sprint Ability test for Badminton players (MRSAB). The present review should serve as a reference standard for RRSA tests. Further research should be directed towards creating and validating more specific RRSA tests protocols to each sports physiological and physical demands.

The Relationship Between Physical Characteristics and Maximal Strength in Men Practicing the Back Squat, the Bench Press and the Deadlift

This study was designed to quantify the relationships between physical characteristics and maximal strength in the back squat, the bench press and the deadlift on powerlifters and football players. Eighteen male junior drug-tested classic powerlifters and seventeen NCAA Division II American football players' anthropometric measurements were taken to compare them with maximal strength results from either a powerlifting meet or testing from their supervised strength and conditioning program. Pearson's bivariate correlations analysis revealed (statistical significance was set at p<0.05) that individuals with a greater (Wilks points) back squat, generally presented a higher Bodyweight (BW) (r=0.37), Body Mass Index (BMI) (r=0.45), Bodyfat Percentage (BF%) (r=0.36), Hip (r=0.41), Waist (r=0.35) and Torso (r=0.41) Circumference (C), Hip C/Height (r=0.46), Waist C/Height (r=0.39) and Torso C/Height (r=0.45) ratios. The individuals with a greater bench press generally presented a higher BMI (r=0.37), Lean Body Weight (LBW) (r=0.36), Hip C (r=0.39) and Hip C/Height ratio (r=0.39). On the other hand, individuals with a greater deadlift were generally older (r=0.34), shorter (r=-0.41), had shorter thighs (r=-0.52) and trunks (r=-0.36), smaller Thigh Length (L)/Height ratio (r=-0.44), Waist C/Hip C (r=-0.41) and Thigh L/Lower Leg L (r=-0.53) ratios, but a higher Lower Leg L/Height ratio (r=-046). The results of this study should be utilized by strength and conditioning coaches to deepen their comprehension of their athletes' physical characteristics in order to help them develop strength through their advantages. Further research should focus on evaluating how physical characteristics affect performance in different squat, bench, and deadlift stances.

Contrast Training Generates Post-Activation Potentiation and Improves Repeated Sprint Ability in Elite Ice Hockey Players

The purpose of this study was to measure the generating effects of Contrast Training (CT) on 6-hour post-activation potentiation (PAP) and its influence on jumping and on on-ice repeated sprint performance in ice hockey players. Forty-one participants were divided in two groups: experimental (EG) and control group (CG). The EG followed the CT PAP protocol which consisted of 5 sets of 5 half inertia back squat superset with 6 squat jumps. The effects of PAP were measured with the vertical countermovement jump (CMJ), stationary broad jump (BJ) and 9 repeated on ice 40-meter maximal sprints with hockey equipment. Results showed that the PAP generated by the CT protocol had no significant impact (p ≥ 0.05) on CMJ, BJ, blood lactate concentration, heart rate peak and rated perceived exertion as EG and CG group presented no significant differences in improvement. However, results show that there was a significant improvement (p < 0.05) for the EG in the total sprint time (-5.5 ± 2.6%; 56.2 ± 4.7 to 53.1 ± 3.9sec) mean sprint speed (+5.9 ± 3.0%; 6.4 ± 0.5 to 6.8 ± 0.5m/s) and in 1st sprint speed (+7.4% ± 5.9; 7.3 ± 0.7 to 7.8 ± 0.6m/s), but not for the CG (-1.4 ± 5.1%; 58.0 ± 5.4 to 57.2 ± 6.4sec), (+1.7 ± 5.1 %; 6.3 ± 0.6 to 6.4 ± 0.6m/s) and (+1.9 ± 7.7%; 6.9 ± 0.7 to 7.0 ± 0.7m/s) respectively. Thus, results show that the CT protocol utilized in this study generated PAP which had an acute effect on the on-ice hockey repeated sprint test performance. Therefore, CT could be utilized punctually to improve repeated sprint performance of elite hockey players as it could potentially help create odd man rushes during games.

Ethical consideration and feasibility demonstration of high-intensity interval training without the use of electrical shocks in mice with and without doxorubicin exposition

INTRODUCTION

Most protocols intended to stimulate cardiovascular training in mice use electrical shocks that cause psychological stress and interfere with running performance. The aim of this study was to: 1) demonstrate the feasibility of a two-week high-intensity interval training (HIIT) program without the use of electric shocks in mice and 2) show that HIIT without electric shocks is feasible in the specific context of mice exposed to chemotherapy (i.e., doxorubicin).

METHODS

Ten C57bl/6 6-week-old female mice underwent a maximal exercise capacity test before and after two weeks of HIIT (five sessions per week) to measure their maximum running speed. The electrical stimulus was substituted by gently lifting the hind legs of the training mice using a tongue depressor. A second sample of ten C57bl/6 10-week-old female mice receiving a single intravenous injection of 20 mg/kg of doxorubicin underwent a single session of HIIT post-DOX using the same gentle stimulation method.

RESULTS

After two weeks of HIIT without the use of electric shocks, non-treated mice had a significant increase in their maximal speed (4.4 m•min^-1; P = 0.019). In DOX-treated mice, the compliance rate to run went from 100% during the acclimation period prior to doxorubicin treatment to 100% when HIIT was performed after the DOX treatment. Doxorubicin treatment seemed to affect exercise compliance in DOX-treated mice. Our study demonstrated that a two-week HIIT program in non-treated mice and a single HIIT session in DOX-treated mice are feasible.

CONCLUSION

The use of electric shocks was not required to obtain acceptable exercise compliance and a significant change in mice physical capacity. Our technique to perform a treadmill maximal exercise capacity test was shown to be feasible, even in specific pathological conditions like chemotherapy infusion, and could become a reference for future research protocols aimed at reducing the impact of psychological stress caused by electric shocks in mice. This model of exercise training in mice introduces an alternative to ethical conduct standards in animal research.

Cardiorespiratory demand and rate of perceived exertion during overground walking with a robotic exoskeleton in long-term manual wheelchair users with chronic spinal cord injury: A cross-sectional study

BACKGROUND

Many wheelchair users adopt a sedentary lifestyle, which results in progressive physical deconditioning with increased risk of musculoskeletal, cardiovascular and endocrine/metabolic morbidity and mortality. Engaging in a walking program with an overground robotic exoskeleton may be an effective strategy for mitigating these potential negative health consequences and optimizing fitness in this population. However, additional research is warranted to inform the development of adapted physical activity programs incorporating this technology.

OBJECTIVES

To determine cardiorespiratory demands during sitting, standing and overground walking with a robotic exoskeleton and to verify whether such overground walking results in at least moderate-intensity physical exercise.

METHODS

We enrolled 13 long-term wheelchair users with complete motor spinal cord injury in a walking program with an overground robotic exoskeleton. Cardiorespiratory measures and rate of perceived exertion (RPE) were recorded by using a portable gas analyzer system during sitting, standing and four 10m walking tasks with the robotic exoskeleton. Each participant also performed an arm crank ergometer test to determine maximal cardiorespiratory ability (i.e., peak heart rate and O₂ uptake [HR_peak, VO_2peak]).

RESULTS

Cardiorespiratory measures increased by a range of 9%-35% from sitting to standing and further increased by 22%-52% from standing to walking with the robotic exoskeleton. During walking, median oxygen cost (O_2Walking), relative HR (%HR_peak), relative O₂ consumption (%VO_2peak) and respiratory exchange ratio (RER) reached 0.29mL/kg/m, 82.9%, 41.8% and 0.9, respectively, whereas median RPE reached 3.2/10. O_2Walking was moderately influenced by total number of sessions and steps taken with the robotic exoskeleton since the start of the walking program.

CONCLUSION

Overground walking with the robotic exoskeleton over a short distance allowed wheelchair users to achieve a moderate-intensity level of exercise. Hence, an overground locomotor training program with a robotic exoskeleton may have cardiorespiratory health benefits in the population studied.

Acute breathing patterns in healthy and heart disease participants during cycling at different levels of immersion

We aimed to determine the effect of aquatic cycling and different levels of immersion on respiratory responses in healthy and heart disease (HD) volunteers. Thirty-four age matched volunteers, 21 HD and 13 healthy controls (HC) took part in this study. The ventilatory pattern, phase 1V_E and steady-state ventilatory responses to progressive exercise from 40 to peak rpm, were measured while participants exercised on a water stationary bike (WSB) at different levels of immersion. No effect of immersion was observed on steady-state respiratory responses in the HD group, but immersion reduced V_E phase 1 by ∼79% at pedaling cadences of 40, 50 and 60rpm. In conclusion, immersion at hips and xiphoid process blunted the fast drive to breathe in the HD group. This transient effect on the respiratory response to immersed exercise cannot be considered a contraindication for exercise in HD individuals.

Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality

This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (P_ext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30 ± 7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial P_ext on DE was 25 W and was increased by 25 W/min at a pedalling cadence between 60 and 80 rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial P_ext deployment was at a cadence of 40 rpm which was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5 min. Maximal HR (DE: 176 ± 15 vs. IE 169 ± 12 bpm) reached by the subjects in the two conditions did not differ (P > .05). Parasympathetic reactivation parameters (ΔHR from 10 to 300 s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10-Δ60 s, P < .05), but similar in the late phase (HRR at Δ120-Δ300 s, P > .05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants.

Biomechanical analysis to determine the external power output on an immersible ergocycle

The external power output (Pext) is unknown during chest-level immersion exercise on water immersible ergocycles (IE). This knowledge will allow the practitioner to prescribe accurately exercise on an IE to the same workload on dryland ergocycle (DE). To develop a mathematical model to calculate Pext during chest-level immersion exercise on IE at different pedalling rates (rpm) taking into account the water external force exerted on the legs and pedalling mechanism. Thirty healthy participants (age: 33 ± 10 years) performed a maximal incremental exercise test on IE (chest-level immersion) and on a DE. Pedalling rate was increased by 10 rpm every minute beginning at 40 till 120 rpm. Pext was calculated by applying the general fluid equation [Formula: see text] on all elements exposed to water external force exertions (legs and pedalling system). Regression analysis yielded the following equations to determine (1) IE Pext (W) based on pedalling rate (rpm): Pext (W) = 0.0004 (rpm)(2.993) (r(2) = 0.99, SEE = 7.6 W, p < 0.0001) and (2) when DE Pext (W) is known, IE pedalling rate (rpm) = 13.91 × DE Pext (W)(0.329) (r(2) = 0.99, SEE = 1.5 W, p < 0.0001). This study provides a mathematical model based on the general fluid equation to calculate IE Pext during chest-level immersion exercise using pedalling rate (rpm), IE pedalling system physical characteristics and lower limb size. This model can be used to determine Pext for any IE type for exercise training prescription.

Increased cardiovascular risk factors in breast cancer survivors identified by routine measurements of body composition, resting heart rate and arterial blood pressure

Purpose

The main objective of this prospective study was to obtain a better understanding of the body composition and vital sign measures of cancers survivors (CS) when compared to regular (R) patients.

Methods

A total of 9,315 female patients were evaluated: 476 CS and 8,839 R patients. Kinesiologists worked side by side with the medical/oncology team to collect a number of base-line measurements on body composition, resting heart rate, and blood pressure as part of the standard intake evaluation during the female patients’ annual checkup.

Results

CS were more likely to have a higher BMI (P = 0.001) and a larger waist circumference (P = 0.001) than R patients. CS were also shown to have higher blood pressure values: diastolic pressure of 76.9 mmHg ± 10.5 VS 75.5 mmHg ± 9.9, (P = 0.01) and systolic pressure of 129.8 mmHg ± 17.2 VS 126.7 mmHg ±17.4 (P = 0.001) compared to R patients, respectively. Regression analysis looking at the relationship between mean arterial pressure and waist circumference did not show any difference between the two groups (CS vs R).

Conclusion

CS who had a higher BMI, a larger waist circumference and higher blood pressure levels, are probably at greater risk for developing cardiovascular disease, diabetes, various musculoskeletal problems as well as an increased risk for various forms of cancers including reoccurrence of previously treated cancer when compared to R patients. Changes in body composition should be considered by the medical team when looking at preventative healthcare strategies for their CS patients.

The impact treatment has on cardiovascular risks factors for breast cancer survivors

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Background: The Integrative Health and Wellness center at VM Medical was established to monitor the body composition, activity level and vital signs of both the regular patients and the cancer survivors during their annual mammography screening. To determine if body composition and basic cardiovascular function of cancer survivors may vary depending on the type of adjuvant therapy dispensed. Methods: Kinesiologists performed base line measurements on 4,414 patient at The VM Medical Breast Center. Measurements were obtained on 3,674 non-oncology female patients and 740 cancer survivors. The data included BMI, resting heart rate, blood pressure, total body fat, lean muscle and waist circumference. The cancer survivors were stratified into 8 different groups (G1-G8) according to the type of surgery they underwent and compared to the regular patients(R). A one way ANOVA was performed with Dunnet post hoc analysis, significance was set at p < 0.05. The two largest groups were; women who underwent surgery, chemotherapy, radiotherapy and hormone therapy (G5) 243 patients, as part of their treatment and women who underwent surgery, radiotherapy and hormone therapy (G6) 207 patients, as part of their treatment. The other 290 patients were separated into the other 6 treatment groups. Results: Significant differences were seen between the cancer survivors in all groups and the regular patients with p= 0.00 in 7 key variables. BMI(F=4.30) µ= 26.08 (R) vs µ= 27.10 (G6), resting heart rate (F= 6.24) µ= 73.04 bts/min (R) vs µ= 76.45 bts/min (G5), diastolic blood pressure (F= 4.65) µ= 74.18 mmHg (R) vs µ= 77.00 mmHg (G5), systolic blood pressure (F= 8.75) µ= 123.04 mmHg (R) vs µ= 130.14 mmHg (G6), lean muscle (F= 3.48) µ= 10.09 kgs (R) vs µ= 9.74 kgs (G6), total body fat (F=9.02) µ= 34.45% (R) vs µ= 37.49% (G6) and waist circumference (F= 4.44) µ= 84.91 cm (R) vs µ= 87.68 cm (G5). Conclusions: It would appear that different treatment protocols are associated with an increase in negative body composition and blood pressure measurements in cancer survivors. This information is important for the medical team to consider when directing the cancer survivors on healthy lifestyle choices post treatment.