A short cycle ergometer test to predict maximal workload and maximal oxygen uptake

Effects of branched chain amino acids, l-citrulline, and alpha-glycerylphosphorylcholine supplementation on exercise performance in trained cyclists: a randomized crossover trial

BACKGROUND

Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance.

METHODS

In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period.

RESULTS

There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test.

CONCLUSIONS

The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.

Training History, Cardiac Autonomic Recovery from Submaximal Exercise and Associated Performance in Recreational Runners

This study investigated the effect of prolonged exertion on cardiac parasympathetic (cPS) reorganization and associated aerobic performance in response to repeated short-lasting submaximal exercise bouts (SSE) performed for 7 days following prolonged exertion. In 19 recreational runners, heart rate (HR) and HR variability (HRV) indices (lnRMSSD, lnHF, and lnLF/HF) were monitored pre- and post-submaximal graded cycling performed on consecutive days following a half-marathon (HM) and compared with the baseline, pre-HM values. Additionally, HR recovery (HRR), aerobic performance, and rate of perceived exertion (RPE) were determined. HR, HRV indices, and HRR were tested for correlation with exercise performance. A significant time effect was found in HR, HRR, and HRV indices as well as in aerobic performance and RPE during the study period. Most of the measured parameters differed from their baseline values only on the same day following HM. However, HRR and HR measured in recovery after SSE were additionally affected one day following the half-marathon yet in opposite directions to those recorded on the same day as the HM. Thus, postSSE HR and HRR exhibited a bivariate time response (postSSE HR: 102 ± 14 bpm; p < 0.001; 82 ± 11 bpm; p = 0.007 vs. 88 ± 11 bpm; HRR in 30 s after SSE cessation: 14.9 ± 4.9 bpm; p < 0.001; 30.1 ± 13.3 bpm; p = 0.006 vs. 24.4 ± 10.8 bpm), potentially indicating a cPS dysfunction phase on the same day and cPS rebound phase one day following HM reflected also in consecutive changes in aerobic power. Correlations were found between the changes in measured cardiac indices with respect to baseline and the changes in aerobic performance indices throughout the study period. The effect of exercise history on cPS reorganization is more pronounced in response to SSE than at rest. Accordingly, we conclude that SSE performed repeatedly on a daily basis following prolonged exertion offers a noninvasive tool to evaluate the impact of training history on cPS recovery and associated aerobic power output in recreational athletes.

Validity and reproducibility of VO2 max testing in a respiration chamber

The aim of this study was to investigate whether VO₂max can be accurately measured in a respiration chamber. Thirty participants aged 23.4 ± 3.9 years with a wide range in VO₂max were included. Participants performed four incremental cycle ergometer tests (VO₂max) with a minimum of 5 days between tests. These tests consisted of one familiarization test with face mask, followed by two VO₂max tests in the respiration chamber and one test with face mask in randomized order. Oxygen consumption and CO₂ production were measured continuously using Omnical (Maastricht University, the Netherlands) gas analysis system. The mean VO₂max was 3634 ± 766 ml, which resulted in mean VO₂max per lean body mass of 60.8 ± 8.0 ml/kg. Repeated respiration chamber tests showed a high concordance, and no significant differences were detected between tests (Lin's concordance correlation coefficient (Rc) = 0.99; ∆70 ± 302 ml/min; p = .38). There was high concordance between the mean VO₂max from both respiration chamber tests and the mean face mask tests, and no significant difference (Rc = 0.99; ∆41 ± 173 ml/min; p = .22) was observed. The Bland‐Altman plots showed no proportional bias between different tests. In conclusion, the respiration chamber has been found to be a valid and reproducible method for measuring VO₂max. New research opportunities are possible in the respiration chamber, such as maximal exercise testing during 24‐hour measurements.

Abdominal fat distribution measured by ultrasound and aerobic fitness in young Danish men born with low and normal birth weight

Abdominal subcutaneous and visceral adipose tissue thickness was examined by ultrasound in 17 men with low birth weight (LBW) and 26 with normal BW control individuals to determine if abdominal obesity in LBW individuals is due to increased visceral or subcutaneous fat mass/thickness, or both. Men born with LBW had an increased waist-to-hip ratio (P = 0.04), greater abdominal fat thickness (P = 0.05) and increased visceral (VAT) and subcutaneous adipose tissue (SAT) thickness compared with controls, however the latter not statistically significant (P = 0.08, P = 0.10). A significant difference between birth weight groups in both SAT (P = 0.04) and VAT (P = 0.03) was found after adjustment for weight, whereas no significant difference in either SAT (P = 0.93) or VAT (P = 0.30) was found after adjustment for BMI. Increased waist-to-hip ratio in LBW individuals is due to increased total abdominal fat including both subcutaneous and visceral fat.

Whole body vibration exercise in the management of cancer therapy-related morbidities: A systematic review

The purpose of this systematic review was to investigate the effects of whole body vibration (WBV) exercise in the management of cancer therapy-related morbidities. The PubMED and PEDro databases were used to access publications published in English about the use of whole body vibration (WBV) exercises in cancer patients until February 22^nd 2017. The studies included were classified according to the level of evidence (LE) by the National Health and Medical Research Council Hierarchy of evidence and the methodological quality (MQ) by the PEDro scale. The four included studies (2 of them with "high" LE-II and MQ) were performed in patients with different types of cancer (i.e. breast, lung, prostate, solid or hematological), treated with WBV exercise to counteract the cancer therapy-related morbidities. The variables evaluated were muscle activity, subjective rate of perceived exertion, exercise capacity, muscle strength, quality of life, resting urinary incontinence and severity of peripheral neuropathy. Although WBV exercise appears to be a potential treatment procedure of cancer therapy-related morbidities, further additional studies are required to determine specific and tailored protocols to be used in the different stages of the disease.

A method for predicting peak work rate for cycle ergometer and treadmill ramp tests

BACKGROUND

Prediction of peak work rate (WRpeak) for incremental exercise testing (IET) is important to bring subjects to their maximal performance within the recommended 8-12 min. This study developed a novel method for prediction of WRpeak for IET on cycles and treadmills.

METHODS

Peak metabolic equivalent of task (METpred) was predicted based on an existing non-exercise prediction formula, and then, predicted peak work rate (WRpred) was derived from separate formulae for the cycle and the treadmill. Eighteen healthy subjects were included.

RESULTS

In males, there was no difference between WRpred versus WRpeak for both the cycle ergometer (277·7 versus 275·6 W, P = 0·70) and the treadmill (264·1 versus 260·5, P = 0·58). In females, there was no difference between WRpred versus WRpeak for the cycle ergometer (187·1 versus 188·3 W, P = 0·90), but a significant difference was found between WRpred versus WRpeak on the treadmill (178·6 versus 151·9 W, P<0·05). For males, the mean absolute percentage errors for WRpred versus WRpeak were 4·6% and 5·7% for the cycle and treadmill, respectively. For females, the errors were 12·2% and 20·8%. The algorithm was successful in achieving the required duration of 8-12 min in 33 of 36 cases.

CONCLUSIONS

The peak work rate prediction protocol was accurate in male subjects for both the cycle and the treadmill. In female subjects, the method was accurate for the cycle, but systematically overpredicted the peak work rate on the treadmill. The protocol requires further adaptation for females on the treadmill.

Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men

Purpose

The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises.

Methods

Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (W_max) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography.

Results

Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W_max (13.21° ± 4.63° to 20.04° ± 4.76°, p < 0.001) then remained unchanged. LV systolic and diastolic twisting velocities progressively increased with exercise intensity during cycling from rest to 60% W_max (twisting, 88.21° ± 20.51° to 209.05° ± 34.56° s⁻¹, p < 0.0001; untwisting, −93.90 (29.62)° to −267.31 (104.30)° s⁻¹, p < 0.0001). During the knee extension exercise, LV twist remained unchanged with progressive intensity (rest 13.40° ± 4.80° to 75% MVC 16.77° ± 5.54°, p > 0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s⁻¹ to 75% MVC 124.32° ± 34.89° s⁻¹, p < 0.01). Untwisting velocity remained unchanged from rest [−90.60 (27.19)° s⁻¹] to 40% MVC (p > 0.05) then increased from 40 to 75% MVC [−98.44 (43.54)° s⁻¹ to −138.42 (73.29)° s⁻¹, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01).

Conclusion

Cycling increased LV twist to 30% W_max which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise.

Effect of Tinospora cordifolia on physical and cardiovascular performance induced by physical stress in healthy human volunteers

INTRODUCTION

In Ayurveda Tinospora cordifolia (Willd.) Miers., has been used for its Rasayana, Deepana, Jwaranashana, Tridosha Shamaka properties. It is an immunomodulator, useful in stress, hyperlipidemia, pyrexia. T. cordifolia was evaluated for adaptogenic activity in healthy volunteers during exercise.

AIMS

The primary objective of this study was to evaluate the effect of T. cordifolia on physical performance, and secondary objectives were to evaluate muscle power, maximal oxygen consumption, and sympathetic activity in comparison with placebo when subjected to physical stress.

MATERIALS AND METHODS

A total of thirty participants were randomly assigned into three groups (n = 10 each) namely placebo, TC 150 and TC 300. Placebo group received maize starch capsule, TC 150 and TC 300 received 150 mg and 300 mg, respectively of T. cordifolia aqueous extract in capsule form once daily in the morning for 28 days. The assessment was performed at baseline visit, day 14 and 28. Physical stressors were cycle ergometer exercise, Jammer's hand-held dynamometer, and cold pressor tests. Physical performance evaluated was maximum distance and speed, oxygen consumption (VO2 max), and hand grip strength. Cardiovascular response was assessed by multiple heart rate (HR) and blood pressure (BP) measurements during each test.

RESULTS

On day 28, TC 150 mg group showed a significant increase in mean maximum speed compared to placebo. On day 14 and 28, TC 300 mg group showed a significant decrease in mean systolic BP (SBP) and HR on fixed workload exercise compared to placebo. There was significant increasing dose effect of both TC groups on SBP on day 14 and 28 and on HR on day 28 only. On day 14 and 28, TC 300 mg showed a significant decrease in mean HR on the cold pressor test, compared to placebo.

CONCLUSION

T. cordifolia improved physical performance and suppressed over activation of the sympathetic nervous system showing its adaptogenic property.

Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans

PURPOSE

It is usually stated that glycogen is stored in human muscle bound to water in a proportion of 1:3 g. We investigated this proportion in biopsy samples during recovery from prolonged exercise.

METHODS

On two occasions, nine aerobically trained subjects ([Formula: see text] = 54.4 ± 1.05 mL kg(-1) min(-1); mean ± SD) dehydrated 4.6 ± 0.2 % by cycling 150 min at 65 % [Formula: see text] in a hot-dry environment (33 ± 4 °C). One hour after exercise subjects ingested 250 g of carbohydrates in 400 mL of water (REHLOW) or the same syrup plus water to match fluid losses (i.e., 3170 ± 190 mL; REHFULL). Muscle biopsies were obtained before, 1 and 4 h after exercise.

RESULTS

In both trials muscle water decreased from pre-exercise similarly by 13 ± 6 % and muscle glycogen by 44 ± 10 % (P < 0.05). After recovery, glycogen levels were similar in both trials (79 ± 15 and 87 ± 18 g kg(-1) dry muscle; P = 0.20) while muscle water content was higher in REHFULL than in REHLOW (3814 ± 222 vs. 3459 ± 324 g kg(-1) dm, respectively; P < 0.05; ES = 1.06). Despite the insufficient water provided during REHLOW, per each gram of glycogen, 3 g of water was stored in muscle (recovery ratio 1:3) while during REHFULL this ratio was higher (1:17).

CONCLUSIONS

Our findings agree with the long held notion that each gram of glycogen is stored in human muscle with at least 3 g of water. Higher ratios are possible (e.g., during REHFULL) likely due to water storage not bound to glycogen.

Early prediction of the highest workload in incremental cardiopulmonary tests

Incremental tests are widely used in cardiopulmonary exercise testing, both in the clinical domain and in sport sciences. The highest workload (denoted W peak ) reached in the test is key information for assessing the individual body response to the test and for analyzing possible cardiac failures and planning rehabilitation, and training sessions. Being physically very demanding, incremental tests can significantly increase the body stress on monitored individuals and may cause cardiopulmonary overload. This article presents a new approach to cardiopulmonary testing that addresses these drawbacks. During the test, our approach analyzes the individual body response to the exercise and predicts the W peak value that will be reached in the test and an evaluation of its accuracy. When the accuracy of the prediction becomes satisfactory, the test can be prematurely stopped, thus avoiding its entire execution. To predict W peak , we introduce a new index, the CardioPulmonary Efficiency Index (CPE), summarizing the cardiopulmonary response of the individual to the test. Our approach analyzes the CPE trend during the test, together with the characteristics of the individual, and predicts W peak . A K-nearest-neighbor-based classifier and an ANN-based classier are exploited for the prediction. The experimental evaluation showed that the W peak value can be predicted with a limited error from the first steps of the test.

Intense nonpharmacological intervention in subjects with multiple cardiovascular risk factors: decreased fasting insulin levels but only a minor effect on plasma plasminogen activator inhibitor activity

Increased plasma levels of insulin and the fibrinolytic inhibitor, plasminogen activator inhibitor type 1 (PAI-1), are two new cardiovascular risk factors. The extent to which these two risk factors can be affected by nonpharmacological intervention modalities has not been convincingly proven in subjects at high risk for cardiovascular disease. This study assesses the effects on fasting plasma insulin and plasma PAI-1 activity of an intervention program including a low-fat, high-fiber diet and regular daily physical exercise. The intervention was implemented by a 1-month learning and training session in a full-boarding wellness center and included a follow-up evaluation after 12 months. The study was conducted on 108 subjects (31 men and 77 women) referred for multiple risk factor treatment. After 1 month of intense intervention, the physical condition improved significantly, and this effect was maintained during the year. The body mass index (BMI), fasting plasma insulin, and plasma lipids were significantly decreased. In women, PAI-1 activity was significantly reduced. At follow-up study in both sexes, the BMI and fasting insulin were still significantly decreased. In women, PAI-1 activity reverted to the preintervention level. In subjects with multiple risk factors, ie, the insulin resistance syndrome, the plasma insulin level can be reduced by an intense nonpharmacological program. Also, at least in women, plasma PAI-1 activity can be modestly modified. However, the magnitude of the decrease in PAI-1 activity was probably too small to reverse the hypofibrinolytic state characteristic of these subjects.

A new validated endurance performance test

The extensive use of performance tests in diet intervention studies mirrors the importance of such a measurement. Although many different endurance performance tests have been used in the past, the majority of these different protocols has never been validated. In this study reproducibility of three different endurance performance tests was evaluated. Thirty well-trained subjects were matched on age, weight, and Wmax and divided into three subgroups. Each group of subjects performed one of three exercise protocols: protocol (A) consisted of cycling at 75% Wmax until exhaustion. In (B) subjects received a preload of 45 min 70% Wmax and then performed as much work as possible in 15 min. (C) consisted of a time trial, in which subjects had to complete a preset amount of work as fast as possible. Each subject performed one of the trials six times. Coefficient of variation (CV) was calculated for each protocol. CV(A) was 26.6%, CV(B) 3.49%, and CV(C) 3.35%. It was concluded that reproducibility of a test at 75% Wmax until exhaustion is poor and these tests are not reliable. Time trial protocols may result in better performance evaluation.