The effect of exercise on bone mineral density in adult cancer survivors: a systematic review and meta-analysis.

PURPOSE: Certain cancer treatments are associated with bone loss and increased fracture risk. Weight-bearing impact exercise, resistance training or the combination, are recommended to preserve or improve bone mineral density (BMD) inhealthy older adults, but their efficacy in cancer survivors is less well understood. The aim of this systematic review with meta-analysis of randomised control trials (RCT) was to review the evidence regarding the role of exercise to counteract cancer treatment-induced bone loss. METHODS: Four databases were searched systematically with 12 RCTs of at least 6-month duration investigating the effects of exercise on BMD compared to a control group in adult cancer survivors identified. RESULTS: Meta-analysis was completed using available data from six studies enrolling 814 participants, with lumbar spine, femoral neck and/or total hip BMD as the primary outcome measures. Overall, there was no significant benefit of exercise compared to controls on BMD at the lumbar spine (0.0071 g/cm , 95% CI -0.0002 to 0.0145, p = 0.057), femoral neck (0.0044 g/cm , 95% CI -0.0005 to 0.0093, p = 0.077), or total hip (0.0024 g/cm , 95% CI -0.0038 to 0.0086, p = 0.443). Subgroup analysis revealed a positive effect on lumbar spine BMD in three studies implementing a combined resistance and impact exercise intervention (0.015 g/cm , 95% CI 0.003 to 0.028, p = 0.019). CONCLUSIONS: From the evidence available, exercise may not be sufficient to improve bone health in cancer survivors, but given the heterogeneity in the participant characteristics and several exercise programs which may not have been designed to specifically optimise bone health, these findings should be interpreted with caution.

Insulin sensitivity not modulated 24 to 78 h after acute resistance exercise in type 2 diabetes patients.

Resistance exercise is recommended as part of the exercise guidelines to prevent and manage type 2 diabetes (T2D), however, the frequency of exercise required to improve glycaemic control and insulin sensitivity is not clear. We recruited and tested 10 individuals with T2D by collecting a fasting blood sample immediately prior to, a whole-body moderate-high intensity resistance exercise session, and 24, 48 and 72 h afterwards. No changes to estimates of insulin sensitivity (HOMA2), glucose or insulin were observed using a repeated measures analysis of variance (p > 0.05). Further, there were no changes observed to markers of inflammation at 24 h following the resistance exercise session (p > 0.05). These findings suggest that insulin sensitivity is not acutely modified, positively or negatively, at 24, 48 or 72 h after a bout of resistance exercise. Nor are markers of inflammation altered during this time frame in a way that could cause transient insulin resistance.

Insulin sensitivity in response to a single resistance exercise session in apparently healthy individuals.

BACKGROUND: Regular resistance exercise completed for a number of weeks has been shown to increase insulin sensitivity and reduce the risk of diabetes-related complications. However, the acute responses to resistance exercise have not been adequately investigated in relation to training frequency. AIM: To investigate the changes to insulin sensitivity in apparently healthy individuals following a single session of unaccustomed resistance exercise. SUBJECTS AND METHODS: Ten sedentary, apparently healthy individuals performed a baseline oral glucose tolerance test and maximal strength testing. Participants then performed a single session of moderate-high intensity resistance exercise which was followed by 4 consecutive days of oral glucose tolerance testing, for which participants replicated their initial diet. Mean estimated insulin sensitivity change scores from baseline values and their 95% confidence intervals were compared to the previously determined values for a clinically meaningful change. RESULTS: Two participants were identified as having hyperinsulinemia and their data were therefore removed from the main analysis. There was a clinically meaningful increase in insulin response (mean >7237 pmol·l⁻¹·120 min⁻¹) on all days following the exercise session and a clinically meaningful increase in glucose response (mean >81 mmol·l⁻¹·120 min⁻¹) on only the 3rd day following exercise. These changes suggest a potentially adverse short-term effect. Additionally, the 2 individuals with hyperinsulinemia displayed more extreme results. CONCLUSION: These results suggest that insulin sensitivity may be impaired following a single session of unaccustomed resistance exercise for approximately 4 days in healthy untrained, older individuals. Further research is required for individuals with hyperinsulinemia.

Lifestyle guidelines for managing adverse effects on bone health and body composition in men treated with androgen deprivation therapy for prostate cancer: an update.

BACKGROUND: Men treated with androgen deprivation therapy (ADT) for prostate cancer are prone to multiple treatment-induced adverse effects, particularly with regard to a deterioration in bone health and altered body composition including decreased lean tissue mass and increased fat mass. These alterations may partially explain the marked increased risk in osteoporosis, falls, fracture and cardiometabolic risk that has been observed in this population. METHODS: A review was conducted that assessed standard clinical guidelines for the management of ADT-induced adverse effects on bone health and body composition in men with prostate cancer. RESULTS: Currently, standard clinical guidelines exist for the management of various bone and metabolic ADT-induced adverse effects in men with prostate cancer. However, an evaluation of the effectiveness of these guidelines into routine practice revealed that men continued to experience increased central adiposity, and, unless pharmacotherapy was instituted, accelerated bone loss and worsening glycaemia occurred. CONCLUSIONS: This review discusses the current guidelines and some of the limitations, and proposes new recommendations based on emerging evidence regarding the efficacy of lifestyle interventions, particularly with regard to exercise and nutritional factors, to manage ADT-related adverse effects on bone health and body composition in men with prostate cancer.

The role of a video-assisted thoracic approach for rib fixation.

PURPOSE: Rib fixation remains a contentious issue in the current practice of orthopaedic, trauma and thoracic surgeons. Whilst rib fractures are undoubtedly associated with high levels of morbidity and mortality, the optimal surgical approach has not yet been fully elucidated in prospective trials and the volume of procedures performed remains low. METHODS: We evaluated 21 consecutive patients who underwent surgical rib fixation either via a standard thoracotomy approach or following the introduction of a video-assisted technique with minimal thoracic incisions. RESULTS: The average age of patients undergoing rib fixation was 47 and the median length of post-operative stay was 4 days. More than 70 % of patients were found to have concurrent haemothoraces, and 19 % had significant injuries to underlying intra-thoracic structures requiring repair. One patient returned to theatre for persistent blood loss; however, there were no other immediate complications or mortalities. CONCLUSIONS: We discuss the involvement of thoracic surgeons, early assessment of the thoracic cavity with video assistance and optimal peri-operative management with particular reference to cases which demonstrate recent changes in our practice.

Enhancement of 2000-m rowing performance after caffeine ingestion.

PURPOSE: To investigate the effect of caffeine ingestion on short-term endurance performance in competitive rowers. METHODS: In this randomized double-blind crossover study, eight competitive oarsmen (peak oxygen uptake [VO2peak] 4.7+/-0.4 L x min(-1), mean +/- SD) performed three familiarization trials of a 2000-m rowing test on an air-braked ergometer, followed by three experimental trials at 3- to 7-d intervals, each 1 h after ingesting caffeine (6 or 9 mg x kg(-1) body mass) or placebo. Trials were preceded by a standardized warm-up (6 min at 225+/-39 W; 75+/-7.7% VO2peak). RESULTS: Urinary caffeine concentration was similar before ingestion (approximately 1 mg x L(-1)) but rose to 6.2+/-3.6 and 14.5+/-7.0 mg x L(-1) for the low and high caffeine doses, respectively. Plasma free fatty acid concentration before exercise was higher after caffeine ingestion (0.29+/-0.17 and 0.39+/-0.20 mM for 6 and 9 mg x kg(-1), respectively) than after placebo (0.13+/-0.05 mM). Respiratory exchange ratio during the warm-up was also substantially lower with caffeine (0.94+/-0.09 and 0.93+/-0.06 for the low and high dose) than with placebo (0.98+/-0.12). Subjects could not distinguish between treatments before or after the exercise test. Both doses of caffeine had a similar ergogenic effect relative to placebo: performance time decreased by a mean of 1.2% (95% likely range 0.4-1.9%); the corresponding increase in mean power was 2.7% (0.4-5.0%). Performance time showed some evidence of individual differences in the effect of caffeine (SD 0.9%; 95% likely range 1.5 to -0.9%). CONCLUSIONS: Ingestion of 6 or 9 mg x kg(-1) of caffeine produces a worthwhile enhancement of short-term endurance performance in a controlled laboratory setting.

Moderate levels of hypohydration impairs bowling accuracy but not bowling velocity in skilled cricket players.

The effects of exercise-induced hypohydration on the motor skill performance of cricket bowling was examined in seven medium-fast bowlers who performed a random order of two experimental trials. Trials consisted of a bowling test (36 deliveries; PREBOWL) in a thermoneutral (16+/-2 degrees C) environment followed by approximately 1 hr of intermittent exercise in a heated environment (28+/-2 degrees C) and a further thermoneutral bowling test (36 deliveries; POSTBOWL). During one trial fluid intake was restricted (HYPO) whereas in the other, subjects were forced to drink in an effort to maintain euhydration (EUH). During all bowling tests subjects were provided with a fixed target on a cricket pitch and the line, length, and velocity of each delivery was determined. Pre-trial hydration status was confirmed by similar body mass (BM; 89.5+/-13.7 vs. 88.9+/-13.4 kg) and haemoglobin concentration (15.0+/-0.8 vs. 14.8+/-0.8 g.100 ml(-1) for EUH and HYPO, respectively). BM loss was greater in HYPO than EUH (2.48+/-0.58 vs. 0.46+/-0.45 kg). Accordingly, the resultant hypohydration was higher after HYPO than EUH (2.78+/-0.49 vs. 0.47+/-0.41% of BM). Whereas HYPO had no effect on bowling velocity (102+/-4 vs. 105+/-8 km x h(-1)), univariate analyses revealed independent differences for both bowling line (2.9+/-0.5 vs 3.4+/-0.6, P<0.01) and length (2.9+/-0.5 vs 3.4+/-0.6, P<0.01) of delivery after HYPO. We conclude that moderate (-2.8% of BM) exercise-induced hypohydration has minimal effect on maximal bowling velocity, but there is a detrimental effect on skilled motor performance in well-trained subjects.

Reproducibility of multiple repeated oral glucose tolerance tests.

We assessed the oral glucose tolerance test's (OGTT) ability to produce consistent results for estimating insulin sensitivity over four consecutive days. Individual coefficients of variation for OGIS and Stumvoll-ISI were 7.8% and 14.4% with no statistically significant difference between days. Thereby, indicating repeated OGTT's are reliable for estimating insulin sensitivity.

Resistance training improves metabolic health in type 2 diabetes: a systematic review.

This paper systematically reviews the effect of resistance training (RT) on glycemic control and insulin sensitivity in adults with type 2 diabetes. Twenty studies were included, with the volume, frequency and intensity of RT varying markedly. Supervised RT improved glycemic control and insulin sensitivity, however, when supervision was removed compliance and glycemic control decreased. Evidence indicates the mechanisms behind the improvements to glucose tolerance require further elucidation. Although research demonstrates apparent benefits of RT for individuals with diabetes, further research is required to elucidate the minimum effective dose by describing frequency, intensity and the duration of acute and chronic improvements.

Measurement of Na+, K+-ATPase activity in human skeletal muscle.

There are few published measures of Na+,K+-ATPase activity in human skeletal muscle. This study investigated the suitability of the K+-stimulated 3-O-methylfluorescein phosphatase assay for measurement of Na+,K+-ATPase activity in human skeletal muscle. Factors investigated include enzyme kinetics, sample treatment, and ligand concentration. The addition of ouabain blocked maximal K+-stimulated 3-O-methylfluorescein phosphatase (3-O-MFPase) activity, confirming the specificity of the assay. Activity was maximal using a multiple freeze-thaw treatment of the homogenate, a 10 mM KCl activating concentration, and a 3-O-methylfluorescein phosphatase substrate concentration of 160 microM, which is eight times higher than previously reported. From quadriceps muscle biopsies taken from seven healthy untrained subjects, the maximal K+-stimulated 3-O-MFPase activity determined from the homogenates was (mean +/- SE) 292 +/- 10 nmol min-1 . g-1 wet wt (1745 +/- 84 pmol min-1 . mg-1 protein). This value is five times greater than previously published data for human skeletal muscle. The intra-assay variability was 8.1% and the interassay variability was 5.3%. These modifications greatly enhanced the 3-O-MFPase assay, with the improved enzymatic conditions allowing valid, reliable measurement of Na+,K+-ATPase activity in small samples of human skeletal muscle.

Effects of training on potassium, calcium and hydrogen ion regulation in skeletal muscle and blood during exercise.

Ionic regulation is critical to muscle excitation, contraction and metabolism, and thus for muscle function during exercise. This review focuses on the effects of training upon K+, Ca2+ and H+ ion regulation in muscle and K+ regulation in blood during exercise. Training enhances K+ regulation in muscle and blood and reduces muscular fatiguability. Endurance, sprint and strength training in humans induce an increased muscle Na+, K+ pump concentration, usually associated with a reduced rise in plasma [K+] during exercise. Although impaired muscle Ca2+ regulation plays a vital role in fatigue, little is known about possible training effects. In rat fast-twitch muscle, overload-induced hypertrophy and endurance training were associated with reduced sarcoplasmic reticulum Ca2+ uptake, consistent with fast-to-slow fibre transition. In human muscle, endurance and strength training had no effect on muscle Ca2+ ATPase concentration. Whilst muscle Ca2+ uptake, release and Ca2+ ATPase activity were depressed by fatigue, no differences were found between strength athletes and untrained individuals. Muscle H+ accumulation may contribute to fatigue during intense exercise and is also modified by sprint training. Sprint training may increase muscle Lac- and work output with exhaustive exercise, but the rise in muscle [H+] is unchanged or attenuated, indicating a reduced rise in muscle [H+] relative to work performed. Muscle buffering capacity can be dissociated from this improved H+ regulatory capacity after training. Thus, training enhances muscle and blood K+ and muscle H+ regulation during exercise, consistent with improved muscular performance and reduced fatiguability; however, little is known about training effects on muscle Ca2+ regulation during contraction.

Improved 2000-meter rowing performance in competitive oarswomen after caffeine ingestion.

Eight competitive oarswomen (age, 22 +/- 3 years; mass, 64.4 +/- 3.8 kg) performed three simulated 2,000-m time trials on a rowing ergometer. The trials, which were preceded by a 24-hour dietary and training control and 72 hours of caffeine abstinence, were conducted 1 hour after ingesting caffeine (6 or 9 mg á kg-1 body mass) or placebo. Plasma free fatty acid concentrations before exercise were higher with caffeine than placebo (0.67 +/- 0.34 vs. 0.72 +/- 0.36 vs. 0.30 +/- 0.10 mM for 6 and 9 mg á kg-1 caffeine and placebo, respectively; p <.05). Performance time improved 0.7% (95% confidence interval [CI] 0 to 1.5%) with 6 mg á kg-1 caffeine and 1. 3% (95% CI 0.5 to 2.0%) with 9 mg á kg-1 caffeine. The first 500 m of the 2,000 m was faster with the higher caffeine dose compared with placebo or the lower dose (1.53 +/- 0.52 vs.1.55 +/- 0.62 and 1. 56 +/- 0.43 min; p =.02). We concluded that caffeine produces a worthwhile enhancement of performance in a controlled laboratory setting, primarily by improving the first 500 m of a 2,000-m row.

Skeletal muscle oxidative capacity, fiber type, and metabolites after lung transplantation.

Lung transplant (LTx) recipients have a low peak work rate, peak oxygen consumption (V O2peak), and early lactate threshold on incremental exercise. We hypothesized that LTx recipients have reduced oxidative function and altered fiber type proportion in peripheral skeletal muscle. Seven stable LTx recipients and seven age- and sex-matched control subjects were studied. Incremental exercise testing with arterialized venous sampling and a resting quadriceps femoris punch muscle biopsy were performed. Muscle specimens were analyzed for fiber type proportion, metabolites, oxidative and glycolytic enzyme activities, and mitochondrial ATP production rate (MAPR) using standard techniques. The results showed that mean V O2peak in LTx recipients was 52% of control subjects. Compared with the control subjects, LTx skeletal muscle exhibited: (1) a lower MAPR; (2) lower activity of the mitochondrial enzymes glutamate dehydrogenase (GDH), citrate synthase (CS), 2-oxogluterate dehydrogenase (OGDH), and 3-hydroxyacyl-CoA-dehydrogenase (HAD). There was no difference in the activities of anaerobic enzymes, except for higher phosphofructokinase activity; (3) a lower proportion of type I fibers; (4) a higher lactate and inosine monophosphate (IMP) content and a lower ATP content at rest indicating a high reliance on anaerobic metabolism. The reduced type I fiber proportion and severely reduced mitochondrial oxidative capacity may play an important role in exercise limitation after LTx.