Benefits beyond cardiometabolic health: the potential of frequent high intensity 'exercise snacks' to improve outcomes for those living with and beyond cancer.

High intensity interval training (HIIT) has been shown to consistently elicit rapid and significant adaptations in a number of physiological systems, across many different healthy and clinical populations. In addition, there is increasing interest in how some acute, yet transient responses to high intensity exercise potentially reduce the risks of particular diseases. Recent work has shown that discrete, brief bouts of high intensity exercise (termed 'exercise snacks') can improve glucose control and vascular health and thus counter the negative cardiometabolic consequences of prolonged, uninterrupted periods of inactivity. In this brief review, we advance the case, using evidence available from pre-clinical studies in the exercise oncology literature, that brief, frequently completed bouts of high intensity exercise embedded within an individual's overall daily and weekly physical activity schedule, may transiently impact the tumour microenvironment and improve the health outcomes for those who have been diagnosed and treated for cancer.

Exercise and the gut microbiome: implications for supportive care in cancer.

PURPOSE: Growing recognition of the gut microbiome as an influential modulator of cancer treatment efficacy and toxicity has led to the emergence of clinical interventions targeting the microbiome to enhance cancer and health outcomes. The highly modifiable nature of microbiota to endogenous, exogenous, and environmental inputs enables interventions to promote resilience of the gut microbiome that have rapid effects on host health, or response to cancer treatment. While diet, probiotics, and faecal microbiota transplant are primary avenues of therapy focused on restoring or protecting gut function in people undergoing cancer treatment, the role of physical activity and exercise has scarcely been examined in this population. METHODS: A narrative review was conducted to explore the nexus between cancer care and the gut microbiome in the context of physical activity and exercise as a widely available and clinically effective supportive care strategy used by cancer survivors. RESULTS: Exercise can facilitate a more diverse gut microbiome and functional metabolome in humans; however, most physical activity and exercise studies have been conducted in healthy or athletic populations, primarily using aerobic exercise modalities. A scarcity of exercise and microbiome studies in cancer exists. CONCLUSIONS: Exercise remains an attractive avenue to promote microbiome health in cancer survivors. Future research should elucidate the various influences of exercise modalities, intensities, frequencies, durations, and volumes to explore dose-response relationships between exercise and the gut microbiome among cancer survivors, as well as multifaceted approaches (such as diet and probiotics), and examine the influences of exercise on the gut microbiome and associated symptom burden prior to, during, and following cancer treatment.

Exercise-induced changes to the human gut microbiota and implications for colorectal cancer: a narrative review.

Physical activity is associated with reduced risks of colorectal cancer (CRC) incidence, recurrence and mortality. While these findings are consistent, the mechanism/s underlying this association remain unclear. Growing evidence supports the many ways in which differing characteristics of the gut microbiota can be tumourigenic or protective against CRC. CRC is characterised by significant dysbiosis including reduced short chain fatty acid-producing bacteria. Recent findings suggest that exercise can modify the gut microbiota, and these changes are inverse to the changes seen with CRC; however, this exercise-microbiota interaction is currently understudied in CRC. This review summarises parallel areas of research that are rapidly developing: The exercise-gut microbiota research and cancer-gut microbiota research and highlights the salient similarities. Preliminary evidence suggests that these areas are linked, with exercise mediating changes that promote the antitumorigenic characteristics of the gut microbiota. Future mechanistic and population-specific studies are warranted to confirm the physiological mechanism/s by which exercise changes the gut microbiota, and the influence of the exercise-gut interaction on cancer specific outcomes in CRC.

The effects of exercise on the bone health of people with cancer: a systematic review and meta-analysis.

PURPOSE: To determine the pooled effect of exercise on the bone health of people diagnosed with cancer. METHODS: Four electronic databases were systematically searched. Controlled trials that assessed the effect of exercise on the bone mineral density (BMD) or content (BMC) measured by dual-energy x-ray absorptiometry or peripheral quantitative computed tomography in people who had been diagnosed with cancer were included in the study. Random-effect meta-analyses of effect size (ES) were conducted. Sub-group analyses were performed to explore the influence of intervention duration, prescription and participant characteristics. RESULTS: Of 66 full-text articles screened, 22 studies, from 21 interventions, were included (primarily breast/prostate cancer, sample range n = 36-498). When all interventions were grouped, a significant pooled ES was observed for exercise on hip (ES = 0.112, 95% CI: 0.026 to 0.198; p = 0.011) and lumbar spine BMD (ES = 0.269, 95% CI: 0.036 to 0.501; p = 0.024) compared to control. There was also an influence of sex, where females had greater improvements in hip (ES = 0.120, 95% CI: 0.017 to 0.223; p = 0.022) and spine BMD (ES = 0.415, 95% CI: 0.056 to 0.774; p = 0.23) compared to males. CONCLUSION: Overall, exercise regimens of studies included in this review appear to improve bone health at the hip and spine in people diagnosed with cancer. Sub-analyses suggest some influence of sex, where females had greater improvements in BMD compared to males. It is essential that future studies evaluate the dose-response of exercise training on bone health and create exercise protocols that better align with the laws of bone modelling to enhance osteogenic potential.

Comparison of training responses and performance adaptations in endurance-trained men and women performing high-intensity interval training.

The efficacy of high-intensity interval training (HIIT) to elicit physiological and performance adaptations in endurance athletes has been established in men and to a lesser extent in women. This study compared lactate threshold (LT2) and performance adaptations to HIIT between men and women. Nine male and eight female cyclists and triathletes completed trials to determine their LT2 and 40 km cycling performance before, and after 10 HIIT sessions. Each HIIT session consisted of 10 × 90 s at peak power output, separated by 60 s active recovery. Main effects showed that HIIT improved peak power output (p = 0.05; ES: 0.2); relative peak power output (W.kg-1; p = 0.04; ES: 0.3 and W.kg-0.32; p = 0.04; ES: 0.3); incremental time to fatigue (p = 0.01; ES: 0.4), time trial time (p < 0.001; ES: 0.7) and time trial power output (p < 0.001; ES: 0.7) equally in both sexes. Although LT2 power output explained 77% of the performance improvement in women, no variable explained the performance improvement in men, suggesting another mechanism(s) was involved. Although HIIT improved cycling performance in men and women, it might not be appropriate to evaluate the effectiveness of HIIT using the same variables for both sexes.

The non-linear relationship between sum of 7 skinfolds and fat and lean mass in elite swimmers.

Body composition can substantially impact elite swimming performance. In practice, changes in fat and lean mass of elite swimmers are estimated using body mass, sum of seven skinfolds (∑7) and lean mass index (LMI). However, LMI may be insufficiently accurate to detect small changes in body composition which could meaningfully impact swimming performance. This study developed equations which estimate dual-energy x-ray absorptiometry (DXA)-derived lean and fat mass using body mass and ∑7 data. Elite Australian swimmers (n = 44; 18 male, 26 female) completed a DXA scan and standardised body mass and ∑7 measurements. Equations to estimate DXA-derived lean and fat mass based on body mass, ∑7 and sex were developed. The relationships between ∑7, body mass and DXA-derived lean and fat mass were non-linear. Fat mass (Adjusted R2 = 0.91; standard error = 1.0 kg) and lean mass (Adjusted R2 = 0.99; standard error = 1.0 kg) equations were considered sufficiently accurate. Lean mass estimates outperformed the LMI in identifying the correct direction of change in lean mass (82% correct; LMI 71%). Using the accurate estimations produced by these equations will enhance the prescription and evaluation of programmes to optimise the body composition and subsequent performance in swimmers.

The Efficacy of the Lactate Threshold: A Sex-Based Comparison.

Hoffmann, SM, Skinner, TL, van Rosendal, SP, Osborne, MA, Emmerton, LM, and Jenkins, DG. The efficacy of the lactate threshold: A sex-based comparison. J Strength Cond Res 34(11): 3190-3198, 2020-The second lactate threshold (LT2) has previously been associated with endurance performance; however, comparisons between sexes are lacking regarding its efficacy. The aim of this study was to compare LT2 between men and women, specifically regarding its (a) relationship with endurance performance and (b) capacity to establish training and competition intensities. Competitive male (mean ± SD: age, 27.7 ± 4.7 years; V[Combining Dot Above]O2max, 59.7 ± 5.2 ml·kg·min; n = 10) and female (mean ± SD: age, 27.3 ± 6.2 years; V[Combining Dot Above]O2max, 54.5 ± 5.3 ml·kg·min; n = 12) cyclists and triathletes completed an incremental cycle trial to volitional fatigue (for determination of V[Combining Dot Above]O2max and LT2 via the modified D-max method), a constant load (±5%) exercise trial of 30 minutes at LT2 power output, and a 40-km cycle time trial. The LT2 significantly correlated with 40-km cycling performance in both men (r = -0.69 to -0.77; p < 0.01-0.05) and women (r = -0.63 to -0.75; p < 0.01-0.05). All men sustained LT2 power output for 30 minutes, compared with 82% of women. Despite LT2 reflecting a similar heart rate, V[Combining Dot Above]O2, and [La] to those elicited during a 40-km time trial in both men and women, power output at LT2 was 6% higher (p < 0.05) than mean time trial power output in women, with no significant difference in men. Based on these findings, sex-specific recommendations have been suggested in regard to the use of LT2 for establishing performance potential, prescribing endurance training intensities and setting 40-km performance intensity.

Acute high intensity interval exercise reduces colon cancer cell growth.

KEY POINTS: Physical activity is associated with reduced mortality rates for survivors of colorectal cancer. Acute high intensity interval exercise (HIIE) reduced colon cancer cell number in vitro and promoted increases in inflammatory cytokines immediately following exercise. This acute suppression of colon cancer cell number was transient and not observed at 120 minutes post-acute HIIE. The acute effects of exercise may constitute an important mechanism by which exercise can influence colorectal cancer outcomes. ABSTRACT: Physical activity is associated with significant reductions in colorectal cancer mortality. However, the mechanisms by which exercise mediates this anti-oncogenic effect are not clear. In the present study, colorectal cancer survivors completed acute (n = 10) or chronic (n = 10) exercise regimes. An acute high intensity interval exercise session (HIIE; 4 × 4 min at 85-95% peak heart rate) was completed with serum samples collected at baseline, as well as 0 and 120 min post-exercise. For the 'chronic' intervention, resting serum was sampled before and after 4 weeks (12 sessions) of HIIE. The effect of serum on colon cancer cell growth was evaluated by incubating cells (CaCo-2 and LoVo) for up to 72 h and assessing cell number. Serum obtained immediately following HIIE, but not 120 min post-HIIE, significantly reduced colon cancer cell number. Significant increases in serum interleukin-6 (P = 0.023), interleukin-8 (P = 0.036) and tumour necrosis factor-α (P = 0.003) were found immediately following acute HIIE. At rest, short-term HIIE training did not promote any changes in cellular growth or cytokine concentrations. The acute effects of HIIE and the cytokine flux may be important mediators of reducing colon cancer cell progression. Repetitive exposure to these acute effects may contribute to the relationship between exercise and improved colorectal cancer survival.

Peer support for the maintenance of physical activity and health in cancer survivors: the PEER trial - a study protocol of a randomised controlled trial.

BACKGROUND: Despite an overwhelming body of evidence showing the benefits of physical activity (PA) and exercise for cancer survivors, few survivors meet the exercise oncology guidelines. Moreover, initiating, let alone maintaining exercise programs with cancer survivors continues to have limited success. The aim of this trial is to evaluate the influence of peer support on moderate-to-vigorous PA (MVPA) and various markers of health 12 months following a brief supervised exercise intervention in cancer survivors. METHODS: Men and women previously diagnosed with histologically-confirmed breast, colorectal or prostate cancer (n = 226), who are >1-month post-treatment, will be invited to participate in this trial. Once enrolled, participants will complete 4 weeks (12 sessions) of supervised high intensity interval training (HIIT). On completion of the supervised phase, both groups will be provided with written recommendations and verbally encouraged to achieve three HIIT sessions per week, or equivalent exercise that meets the exercise oncology guidelines. Participants will be randomly assigned to receive 12 months of peer support, or no peer support (control). Primary and secondary outcomes will be assessed at baseline, after the 4-week supervised HIIT phase and at 3-, 6- and 12-months. Primary outcomes will include accelerometry-derived MVPA and prescribed HIIT session adherence; whilst secondary outcomes will include cardiorespiratory fitness ([Formula: see text]), body composition, quality of life and select cytokines, myokines and inflammatory markers. Random effects mixed modelling will be used to compare mean changes in outcomes between groups at each time point. A group x time interaction will be used to formally test for differences between groups (alpha =0.05); utilising intention-to-treat analyses. DISCUSSION: If successful, peer support may be proposed, adopted and implemented as a strategy to encourage cancer survivors to maintain exercise beyond the duration of a short-term, supervised intervention. A peer support-exercise model has the long-term potential to reduce comorbidities, improve physical and mental wellbeing, and significantly reduce the burden of disease in cancer survivors. ETHICS: Human Research Ethics Committee of Bellberry Ltd. (#2015-12-840). TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry 12618001855213 . Retrospectively registered 14 November 2018. Trial registration includes all components of the WHO Trial Registration Data Set, as recommended by the ICMJE.

Nutrition therapy for the management of cancer-related fatigue and quality of life: a systematic review and meta-analysis.

Cancer-related fatigue (CRF) is one of the most commonly reported disease- and treatment-related side effects that impede quality of life. This systematic review and meta-analysis describes the effects of nutrition therapy on CRF and quality of life in people with cancer and cancer survivors. Studies were identified from four electronic databases until September 2017. Eligibility criteria included randomised trials in cancer patients and survivors; any structured dietary intervention describing quantities, proportions, varieties and frequencies of food groups or energy and macronutrient consumption targets; and measures of CRF and quality of life. Standardised mean differences (SMD) were pooled using random-effects models. The American Dietetic Association's Evidence Analysis Library Quality Checklist for Primary Research was used to evaluate the methodological quality and risk of bias. A total of sixteen papers, of fifteen interventions, were included, comprising 1290 participants. Nutrition therapy offered no definitive effect on CRF (SMD 0·18 (95 % CI -0·02, 0·39)) or quality of life (SMD 0·07 (95 % CI -0·10, 0·24)). Preliminary evidence indicates plant-based dietary pattern nutrition therapy may benefit CRF (SMD 0·62 (95 % CI 0·10, 1·15)). Interventions using the patient-generated subjective global assessment tool and prescribing hypermetabolic energy and protein requirements may improve quality of life. However, the heterogeneity seen in study design, nutrition therapies, quality-of-life measures and cancer types impede definitive dietary recommendations to improve quality of life for cancer patients. There is insufficient evidence to determine the optimal nutrition care plan to improve CRF and/or quality of life in cancer patients and survivors.

Feasibility, acceptability and efficacy of a text message-enhanced clinical exercise rehabilitation intervention for increasing 'whole-of-day' activity in people living with and beyond cancer.

BACKGROUND: Exercise interventions are typically delivered to people with cancer and survivors via supervised clinical rehabilitation. However, motivating and maintaining activity changes outside of the clinic setting remains challenging. This study investigated the feasibility, acceptability and efficacy of an individually-tailored, text message-enhanced intervention that focused on increasing whole-of-day activity both during and beyond a 4-week, supervised clinical exercise rehabilitation program for people with cancer and survivors. METHODS: Participants (n = 36; mean ± SD age 64.8 ± 9.6 years; 44.1 ± 30.8 months since treatment) were randomized 1:1 to receive the text message-enhanced clinical exercise rehabilitation program, or the standard clinical exercise rehabilitation program alone. Activity was assessed at baseline, 4-weeks (end of the standard program) and 12-weeks (end of enhanced program) using both device (activPAL accelerometer; sitting, standing, light-stepping, moderate-stepping) and self-report [Multimedia Activity Recall for Children and Adults (MARCA); sedentary, light, moderate-to-vigorous physical activity (MVPA)] methods. The MARCA also assessed time use domains to provide context to activity changes. Changes and intervention effects were evaluated using linear mixed models, adjusting for baseline values and potential confounders. RESULTS: The study had high retention (86%) and participants reported high levels of satisfaction [4.3/5 (±0.8)] with the intervention. Over the first 4 weeks, MARCA-assessed MVPA increased [+ 53.2 (95%CI: 2.9, 103.5) min/d] between groups, favoring the text message-enhanced program, but there were no significant intervention effects on sedentary behavior. By 12 weeks, relative to the standard group, participants in the text message-enhanced group sat less [activPAL overall sitting: - 48.2 (- 89.9, - 5.6) min/16 h awake; MARCA: -80.1 (- 156.5, - 3.8) min/d] and were participating in more physical activity [activPAL light stepping: + 7.0 (0.4, 13.6: min/16 h awake; MARCA MVPA: + 67.3 (24.0, 110.6) min/d]. The time-use domains of Quiet Time [- 63.3 (- 110.5, - 16.0) min/d] and Screen Time [- 62.0 (- 109.7, - 14.2) min/d] differed significantly between groups. CONCLUSIONS: Results demonstrate feasibility, acceptability and efficacy of a novel, text message-enhanced clinical exercise rehabilitation program to support changes in whole-of-day activity, including both physical activity and sedentary behavior. Changes were largely seen at 12-week follow-up, indicating potential for the intervention to result in continued improvement and maintenance of behavior change following a supervised exercise intervention. TRIAL REGISTRATION: This trial is registered with the Australian New Zealand Clinical Trials Registry ( ACTRN12616000641493 ; date registered 17/5/16).

Efficacy of Exercise Interventions in Patients With Advanced Cancer: A Systematic Review.

OBJECTIVE: To critically analyze the literature surrounding the efficacy of exercise interventions in patients with advanced cancer. DATA SOURCES: A literature search was undertaken of health and medical electronic databases (PubMED, Medline, CINAHL, Embase, PEDRO, Web of Science, Scopus) until March 1, 2017. STUDY SELECTION: Studies were included if they were published in the English language and met the following criteria: structured exercise as the primary intervention, ≥80% study participants diagnosed with advanced cancer that is unlikely to be cured; reported outcomes concerning physical function, quality of life, fatigue, body composition, psychosocial function, sleep quality pain, and/or survival. DATA EXTRACTION: After title and abstract screening, 68 articles were eligible for full-text review, with a total of 25 studies (n=1188; 16 controlled trials, 9 noncontrolled trials) included in the quantitative synthesis. Two reviewers assessed methodological quality using the Cochrane Risk of Bias Tool for controlled trials and a modified Newcastle-Ottawa Scale for noncontrolled trials. DATA SYNTHESIS: Aerobic exercise was used in 6 studies, resistance training in 3 studies, and combination training (aerobic and resistance) in 15 studies. Significant between- and within-group improvements were reported with exercise in ≥50% of studies assessing physical function (83%), quality of life (55%), fatigue (50%), body composition (56%), psychosocial function (56%), and sleep quality (100%). Improvement within or between groups in pain after exercise was only observed in 2 studies (25%), whereas survival was unaffected in any study. CONCLUSIONS: Most studies reported significant between- and/or within-group improvements in physical function, quality of life, fatigue, body composition, psychosocial function, and sleep quality in patients with advanced cancer, although the effects on pain and survival rates are unclear. Exercise appears to be an effective adjunct therapy in the advanced cancer context, although targeted studies are required to determine the optimal exercise dose to enhance outcomes for specific cancer diagnoses.

Tear osmolarity is sensitive to exercise-induced fluid loss but is not associated with common hydration measures in a field setting.

This investigation (i) examined changes in tear osmolarity in response to fluid loss that occurs with exercise in a field setting, and (ii) compared tear osmolarity with common field and laboratory hydration measures.  Sixty-three participants [age 27.8 ± 8.4 years, body mass 72.15 ± 10.61 kg] completed a self-paced 10 km run outside on a predetermined course. Body mass, tear fluid, venous blood and urine samples were collected immediately before and after exercise.  Significant (p < 0.001) reductions in body mass (1.71 ± 0.44%) and increases in tear osmolarity (8 ± 15 mOsm.L-1), plasma osmolality (7 ± 8 mOsm.kg-1), and urine specific gravity (0.0014 ± 0.0042 g.mL-1; p = 0.008) were observed following exercise. Pre- to post-exercise change in tear osmolarity was not significantly correlated (all p > 0.05) with plasma osmolality (rs = 0.24), urine osmolality (rs = 0.14), urine specific gravity (rs = 0.13) or relative body mass loss (r = 0.20).  Tear osmolarity is responsive to exercise-induced fluid loss but does not correlate with the changes observed using other common measures of hydration status in the field setting. Practitioners shouldn't directly compare or replace other common hydration measures with tear osmolarity in the field. ABBREVIATIONS: BML: Body Mass Loss; CV: Coefficient of Variation; Posm: Plasma osmolality; SD: Standard Deviation; Tosm: Tear Osmolarity; Uosm: Urine Osmolality; USG: Urine Specific Gravity; WBGT: Wet bulb globe thermometer.

Nutrition therapy with high intensity interval training to improve prostate cancer-related fatigue in men on androgen deprivation therapy: a study protocol.

BACKGROUND: Cancer-related fatigue is one of the most prevalent, prolonged and distressing side effects of prostate cancer treatment with androgen deprivation therapy. Preliminary evidence suggests natural therapies such as nutrition therapy and structured exercise prescription can reduce symptoms of cancer-related fatigue. Men appear to change their habitual dietary patterns after prostate cancer diagnosis, yet prostate-specific dietary guidelines provide limited support for managing adverse side effects of treatment. The exercise literature has shown high intensity interval training can improve various aspects of health that are typically impaired with androgen deprivation therapy; however exercise at this intensity is yet to be conducted in men with prostate cancer. The purpose of this study is to examine the effects of nutrition therapy beyond the current healthy eating guidelines with high intensity interval training for managing cancer-related fatigue in men with prostate cancer treated with androgen deprivation therapy. METHODS/DESIGN: This is a two-arm randomized control trial of 116 men with prostate cancer and survivors treated with androgen deprivation therapy. Participants will be randomized to either the intervention group i.e. nutrition therapy and high intensity interval training, or usual care. The intervention group will receive 20 weeks of individualized nutrition therapy from an Accredited Practising Dietitian, and high intensity interval training (from weeks 12-20 of the intervention) from an Accredited Exercise Physiologist. The usual care group will maintain their standard treatment regimen over the 20 weeks. Both groups will undertake primary and secondary outcome testing at baseline, week 8, 12, and 20; testing includes questionnaires of fatigue and quality of life, objective measures of body composition, muscular strength, cardiorespiratory fitness, biomarkers for disease progression, as well as dietary analysis. The primary outcomes for this trial are measures of fatigue and quality of life. DISCUSSION: This study is the first of its kind to determine the efficacy of nutrition therapy above the healthy eating guidelines and high intensity interval training for alleviating prostate-cancer related fatigue. If successful, nutrition therapy and high intensity interval training may be proposed as an effective therapy for managing cancer-related fatigue and improving quality of life in men during and after prostate cancer treatment. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12615000512527 . Trial registered on the 22/5/2015.

Safety and feasibility of exercise interventions in patients with advanced cancer: a systematic review.

GOALS OF WORK: The beneficial effects of exercise in cancer patients are reasonably well-established, although research in this field has predominantly investigated cancer patients in the earlier stages of disease. However, the most recent evidence surrounding exercise interventions in advanced cancer populations has yet to be systematically evaluated. This review critically analyses the safety and feasibility of exercise interventions in patients with advanced cancer. METHODS: All randomised, non-randomised and prospective observational trials of exercise training interventions in patients with advanced cancer were included. 'Safety' was defined as the number and severity of reported adverse events during exercise training. 'Feasibility' was determined by participant adherence, attendance and/or study completion rates. RESULTS: A total of 25 studies involving 1088 patients were included: 16 randomised controlled and nine prospective observational cohort trials. Seven studies included advanced lung cancer patients exclusively, while eight involved patients with various cancer diagnoses. Aerobic exercise was investigated in five studies, resistance training in two studies and combination training (aerobic and resistance) in 14 studies. Six minor adverse events were reported due to exercise. All of these were musculoskeletal in nature, resulting in two participants' withdrawal from the study. Exercise adherence ranged from 65 to 89% but was only described in nine studies. Attendance at each exercise session was described in a further nine studies, ranging from 59 to 100%. CONCLUSIONS: Implementation of exercise interventions appears to be safe and feasible in advanced cancer clinical practice, although targeted studies are required to determine the optimal exercise dose for specific cancer diagnoses.

Velocity, aerobic power and metabolic cost of whole body and arms only front crawl swimming at various stroke rates.

PURPOSE: Stroke rate (SR) has not been considered in previous research examining the relative roles of the limbs in front-crawl performance. This study compared velocity, aerobic power ([Formula: see text]) and metabolic cost (C) between whole body (WB) and arms only (AO) front-crawl swimming across various intensities while controlling SR. METHODS: Twenty Australian national swimmers performed six 200 m front-crawl efforts under two conditions: (1) WB swimming and, (2) AO swimming. Participants completed the 200 m trials under three SR conditions: "low" (22-26 stroke-cycles min(-1)), "moderate" (30-34 stroke-cycles min(-1) and "high" (38-42 stroke-cycles min(-1)). [Formula: see text] was continuously measured, with C, velocity, SR, and kick rate calculated for each effort. RESULTS: Regardless of the SR condition and sex, AO velocity was consistently lower than WB velocity by ~11.0 % (p < 0.01). AO [Formula: see text] was lower than WB [Formula: see text] at all SR conditions for females (p < 0.01) and at the "high" SR for males (p < 0.01). C did not differ between WB and AO at any SR for both sexes (p > 0.01). When C was expressed as a function of velocity, WB and AO regression equations differed for males (p = 0.01) but not for females (p = 0.087). Kick rate increased as SR increased (p < 0.01), though the kick-to-stroke rate ratio remained constant. CONCLUSION: Elite swimmers gain ~11 % in velocity from their kick and, when used in conjunction with the arm stroke at the swimmers' preferred frequency, the metabolic cost of WB and AO swimming is the same. Coaches should consider these results when prescribing AO sets if their intention is to reduce the metabolic load.

The Osteogenic Effect of Impact-Loading and Resistance Exercise on Bone Mineral Density in Middle-Aged and Older Men: A Pilot Study.

BACKGROUND: Regular exercise has been recommended as a potential strategy to counteract the age-related bone loss experienced by men; however, the optimal exercise prescription is not known. OBJECTIVE: To perform a pilot study to examine the osteogenic effect, safety and feasibility of a combined program of upper body resistance exercise and two doses of impact-loading exercise on bone mineral density (BMD) of middle-aged and older men. METHODS: Forty-two community-dwelling men aged 50-74 years were randomly assigned to either an exercise program of combined upper body resistance exercise and either high-dose impact-loading (HI; 80 jumps per session) or moderate-dose impact-loading (MOD; 40 jumps per session) or a control (CON) group. The 9-month intervention involved 4 sessions each week: 2 supervised clinic-based and 2 home-based. BMD of the lumbar spine, femoral neck, total hip, trochanter and whole body as well as lean and fat mass were assessed at baseline and 9 months by dual-energy X-ray absorptiometry. Bone turnover markers, hormone levels, physical function and muscle strength were also assessed. RESULTS: Following 9 months of training, significant differences in BMD among groups were found at the total hip (p = 0.010) and trochanter (p = 0.047) with BMD in the MOD group decreasing relative to the HI group. Although not significant, the HI group consistently preserved BMD, whereas BMD of the MOD and CON groups declined at the hip sites. Mean change for all groups at all skeletal sites was approximately within ±1%. There was no change in bone turnover markers. There were no adverse events as a result of the intervention; however, overall attendance for the HI and MOD groups was 53% (clinic: 68%, home: 38%) and 65% (clinic: 74%, home: 55%), respectively. CONCLUSIONS: This study indicates that while impact-loading exercise can be safely undertaken in middle-aged and older men, the current combined program did not elicit significant improvements in BMD.

Metabolic and hormonal responses to isoenergetic high-intensity interval exercise and continuous moderate-intensity exercise.

This study investigated the effects of high-intensity interval training (HIIT) vs. work-matched moderate-intensity continuous exercise (MOD) on metabolism and counterregulatory stress hormones. In a randomized and counterbalanced order, 10 well-trained male cyclists and triathletes completed a HIIT session [81.6 ± 3.7% maximum oxygen consumption (V̇o2 max); 72.0 ± 3.2% peak power output; 792 ± 95 kJ] and a MOD session (66.7 ± 3.5% V̇o2 max; 48.5 ± 3.1% peak power output; 797 ± 95 kJ). Blood samples were collected before, immediately after, and 1 and 2 h postexercise. Carbohydrate oxidation was higher (P = 0.037; 20%), whereas fat oxidation was lower (P = 0.037; -47%) during HIIT vs. MOD. Immediately after exercise, plasma glucose (P = 0.024; 20%) and lactate (P < 0.01; 5.4×) were higher in HIIT vs. MOD, whereas total serum free fatty acid concentration was not significantly different (P = 0.33). Targeted gas chromatography-mass spectromtery metabolomics analysis identified and quantified 49 metabolites in plasma, among which 11 changed after both HIIT and MOD, 13 changed only after HIIT, and 5 changed only after MOD. Notable changes included substantial increases in tricarboxylic acid intermediates and monounsaturated fatty acids after HIIT and marked decreases in amino acids during recovery from both trials. Plasma adrenocorticotrophic hormone (P = 0.019), cortisol (P < 0.01), and growth hormone (P < 0.01) were all higher immediately after HIIT. Plasma norepinephrine (P = 0.11) and interleukin-6 (P = 0.20) immediately after exercise were not significantly different between trials. Plasma insulin decreased during recovery from both HIIT and MOD (P < 0.01). These data indicate distinct differences in specific metabolites and counterregulatory hormones following HIIT vs. MOD and highlight the value of targeted metabolomic analysis to provide more detailed insights into the metabolic demands of exercise.

The effect of knee flexion contracture following total knee arthroplasty on the energy cost of walking.

This study evaluated the energy cost of walking (Cw) with knee flexion contractures (FC) simulated with a knee brace, in total knee arthroplasty (TKA) recipients (n=16) and normal controls (n=15), and compared it to baseline (no brace). There was no significant difference in Cw between the groups at baseline but TKA recipients walked slower (P=0.048) and with greater knee flexion in this condition (P=0.003). Simulated FC significantly increased Cw in both groups (TKA P=0.020, control P=0.002) and this occurred when FC exceeded 20° in the TKA group and 15° in the controls. Reported perceived exertion was only significantly increased by FC in the control group (control P<0.001, TKA P=0.058). Simulated knee FCs less than 20° do not increase Cw or perceived exertion in TKA recipients.