Long-term effectiveness and cost-effectiveness of high versus low-to-moderate intensity resistance and endurance exercise interventions among cancer survivors

PURPOSE

This study aimed to evaluate the long-term effectiveness and cost-effectiveness of high intensity (HI) versus low-to-moderate intensity (LMI) exercise on physical fitness, fatigue, and health-related quality of life (HRQoL) in cancer survivors.

METHODS

Two hundred seventy-seven cancer survivors participated in the Resistance and Endurance exercise After ChemoTherapy (REACT) study and were randomized to 12 weeks of HI (n = 139) or LMI exercise (n = 138) that had similar exercise types, durations, and frequencies, but different intensities. Measurements were performed at baseline (4-6 weeks after primary treatment), and 12 (i.e., short term) and 64 (i.e., longer term) weeks later. Outcomes included cardiorespiratory fitness, muscle strength, self-reported fatigue, HRQoL, quality-adjusted life years (QALYs) and societal costs. Linear mixed models were conducted to study (a) differences in effects between HI and LMI exercise at longer term, (b) within-group changes from short term to longer term, and (c) the cost-effectiveness from a societal perspective.

RESULTS

At longer term, intervention effects on role (β = 5.9, 95% CI = 0.5; 11.3) and social functioning (β = 5.7, 95%CI = 1.7; 9.6) were larger for HI compared to those for LMI exercise. No significant between-group differences were found for physical fitness and fatigue. Intervention-induced improvements in cardiorespiratory fitness and HRQoL were maintained between weeks 12 and 64, but not for fatigue. From a societal perspective, the probability that HI was cost-effective compared to LMI exercise was 0.91 at 20,000€/QALY and 0.95 at 52,000€/QALY gained, mostly due to significant lower healthcare costs in HI exrcise.

CONCLUSIONS

At longer term, we found larger intervention effects on role and social functioning for HI than for LMI exercise. Furthermore, HI exercise was cost-effective with regard to QALYs compared to LMI exercise.

TRIAL REGISTRATION

This study is registered at the Netherlands Trial Register [NTR2153 [ http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2153 ]] on the 5th of January 2010.

IMPLICATIONS FOR CANCER SURVIVORS

Exercise is recommended to be part of standard cancer care, and HI may be preferred over LMI exercise.

Systematic review of exercise training in colorectal cancer patients during treatment

Colorectal cancer surgery results in considerable postoperative morbidity, mortality and reduced quality of life. As many patients will undergo additional (neo)adjuvant therapy, it is imperative that each individual optimize their physical function. To elucidate the potential of exercise in patient optimization, we investigated the evidence for an exercise program before and after surgical treatment in colorectal cancer patients. A systematic review was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions, the guidelines of the Physical Therapy Journal and the PRISMA guidelines. No literature pertaining to exercise training during preoperative neoadjuvant treatment was found. Seven studies, investigating the effects of regular exercise during adjuvant chemotherapy for patients with colorectal cancer or a mixed population, were identified. A small effect (effect size (ES) 0.4) of endurance/interval training and strength training (ES 0.4) was found in two studies conducted in patients with colorectal and gastrointestinal cancer. In five studies that included a mixed population of cancer patients, interval training resulted in a large improvement (ES 1.5; P≤.05). Endurance training alone was found to increase both lower extremity strength and endurance capacity. The effects of strength training in the lower extremity are moderate, whereas, in the upper extremity, the increase is small. There is limited evidence available on exercise training during treatment in colorectal cancer patients. One study concluded exercise therapy may be beneficial for colorectal cancer patients during adjuvant treatment. The possible advantages of training during neoadjuvant treatment may be explored by prehabilitation trials.

Resistance training in cancer survivors: a systematic review

This systematic review summarizes the research of previous studies that used resistance training in the post-treatment phase of cancer patients with a focus on methodological quality, training methods and physical outcome measures. We found twenty-four studies (10 RCTs, 4 controlled clinical trials and 10 uncontrolled trials) that met all inclusion criteria. The studies were of moderate methodological quality. The majority of studies involved breast cancer patients (54%), followed by prostate cancer patients (13%). Most studies used a combination of resistance and aerobic training, which was mostly supervised. Resistance training involved large muscle groups, with 1-3 sets of 8-12 repetitions. The duration of the resistance training programs varied from 3-24 weeks, with a training frequency of 1-5 sessions per week. The training intensity ranged from 25% to 85% of the one-repetition maximum. Overall, positive training effects were observed for cardiopulmonary and muscle function, with significant increases in peak oxygen uptake (range: 6-39%), and in the one-repetition maximum (range: 11-110%). In general, there were no effects of training on body composition, endocrine and immune function, and haematological variables. No adverse effects of the resistance training were reported. Based upon these results, we recommend to incorporate resistance training in cancer rehabilitation programmes.

Impact of anthracycline dose on quality of life and rehabilitation in breast cancer treatment

BACKGROUND

In 2005 the Dutch national guidelines for treatment of breast cancer were updated. From then onwards, patients with operable breast cancer, who formerly received four cycles of adjuvant chemotherapy with doxorubicin/cyclophosphamide (AC), were treated with five cycles of 5-fluorouracil/epirubicin/cyclophosphamide (FEC), based on data suggesting survival benefit.

PRIMARY OBJECTIVE

evaluation of the effect on quality-of-life and trainability after four AC versus five FEC cycles of polychemotherapy.

SECONDARY OBJECTIVE

evaluation of the effectiveness of an 18-week training programme for breast cancer survivors.

METHODS

A prospective cohort study design was used, comparing two chemotherapy regimens historically. The first cohort (group 1) received 4AC (A 60 mg/m2, C 600 mg/m2) (n=25) and the second cohort (group 2) received 5FE C (F 500 mg/m2, E 90 mg/m2, C 500 mg/m2) (n=50) adjuvant polychemotherapy. Both groups completed an 18-week high-intensity strength-training programme. Outcome measures were changes in quality-of-life (EORTC-QLQ-C30, MFI -20), muscular strength (one-repetition maximum; leg press) and cardiopulmonary function (VO2max) between baseline and follow-up.

RESULTS

Between March 2002 and February 2006, 75 female subjects with breast cancer participated in this study. Baseline characteristics were similar in both groups. After completing the training programme, both groups showed a significant improvement in all outcome measures. No significant differences in changes of the EORTC-QLQ-C30 and MFI-20, one repetition maximum of the leg press and the VO2max between the two groups were demonstrated.

CONCLUSION

After adaptation of the Dutch national breast cancer treatment guidelines, patients received prolonged and increased doses of anthracyclines. This, however, did not result in a difference in the baseline situation before rehabilitation and in training response, nor in quality of life between the two groups.

Long-term follow-up after cancer rehabilitation using high-intensity resistance training: persistent improvement of physical performance and quality of life

The short-term beneficial effects of physical rehabilitation programmes after cancer treatment have been described. However, little is known regarding the long-term effects. The purpose of this study was to investigate the long-term effects of high-intensity resistance training compared with traditional recovery. A total of 68 cancer survivors who completed an 18-week resistance training programme were followed for 1 year. During the 1-year follow-up, 19 patients dropped out (14 due to recurrence of cancer). The remaining 49 patients of the intervention group were compared with a group of 22 patients treated with chemotherapy in the same period but not participating in any rehabilitation programme. Outcome measures were muscle strength, cardiopulmonary function, fatigue, and health-related quality of life. One year after completion of the rehabilitation programme, the outcome measures in the intervention group were still at the same level as immediately after rehabilitation. Muscle strength at 1 year was significantly higher in patients who completed the resistance training programme than in the comparison group. High-intensity resistance training has persistent effects on muscle strength, cardiopulmonary function, quality of life, and fatigue. Rehabilitation programmes for patients treated with chemotherapy with a curative intention should include high-intensity resistance training in their programme.

Long-standing, insulin-treated type 2 diabetes patients with complications respond well to short-term resistance and interval exercise training

OBJECTIVE

To determine the feasibility and the benefits of combined resistance and interval exercise training on phenotype characteristics and skeletal muscle function in deconditioned, type 2 diabetes (T2D) patients with polyneuropathy.

DESIGN

Short-term, single-arm intervention trial.

METHODS

Eleven male T2D patients (age: 59.1+/-7.5 years; body mass index: 32.2+/-4.0 kg/m2) performed progressive resistance and interval exercise training thrice a week for 10 weeks. Besides primary diabetes outcome measures, muscle strength (MUST), maximal workload capacity (Wmax), whole-body peak oxygen uptake (VO2peak) and muscle oxidative capacity (MUOX), intramyocellular lipid (IMCL) and glycogen (IMCG) storage, and systemic inflammation markers were determined before and after training. Daily exogenous insulin requirements (EIR) and historic individualized EIR were gathered and analysed.

RESULTS

MUST and Wmax increased with 17% (90% confidence intervals 9-24%) and 14% (6-21) respectively. Furthermore, mean arterial blood pressure declined with 5.5 mmHg (-9.7 to -1.4). EIR dropped with 5.0 IU/d (-11.5 to 1.5) compared with baseline. A decline of respectively -0.7 mmol/l (-2.9 to 1.5) and -147 micromol/l (-296 to 2) in fasting plasma glucose and non-esterified fatty acids concentrations were observed following the intervention, but these were not accompanied by changes in VO2peak, MUOX, IMCL or IMCG, and blood glycolysated haemoglobin, adiponectin, tumor necrosis factor-alpha and/or cholesterol concentrations.

CONCLUSION

Short-term resistance and interval exercise training is feasible in deconditioned T2D patients with polyneuropathy and accompanied by moderate improvements in muscle function and blood pressure. Such a specific exercise regimen may provide a better framework for future exercise intervention programmes in the treatment of deconditioned T2D patients.

Recognising vascular causes of leg complaints in endurance athletes. Part 1: validation of a decision algorithm

Flow limitations in the iliac arteries of endurance athletes during exercise were previously ascribed solely to intravascular lesions. We postulate that functional kinking of the arteries can also result in flow limitations. However, the diagnostic tools in routine practice are not effective in diagnosing such flow limitations in a substantial proportion of athletes, mainly because these diagnostic tools do not measure in the provocative situations. Ninety-two symptomatic legs in 80 endurance athletes were examined with newly developed, sports-specific vascular tests. Thirty-five asymptomatic cyclists matched for working capacity served as the control subjects. Legs were classified as vascular or non-vascular following a decision algorithm, based upon the results of these diagnostic tests, excluding orthopaedic causes by the effects of specific treatment. Independently of this clinical classification, an alternative method was applied to find stable characteristics in the total patient group using factor analysis. This characterisation was based on scores on 14 test variables deriving from diagnostic tests that were not used in the decision algorithm, thus avoiding dependency between the clinical categorisation and the statistical categorisation. The hypothesis was that these characteristics were sufficiently sensitive to classify patients with vascular and non-vascular complaints. If so, these characteristics should correspond with the one derived from the decision algorithm. Following the decision algorithm, 58 legs (63%) were classified as vascular, 29 (32%) as non-vascular and 5 (5%) as inconclusive. The latter were considered non-vascular. In a substantial proportion of the vascular patients, kinking of the iliac arteries was identified as the major cause of flow limitation. The characteristics derived from factor analysis proved to classify 87% in agreement with the decision algorithm (kappa 0.56). The agreement is sufficient for validation of the clinical classification. The algorithm can therefore be applied in clinical situations to diagnose endurance athletes with flow limitations due to both intravascular lesions and kinking of the arteries.

Recognising vascular causes of leg complaints in endurance athletes. Part 2: the value of patient history, physical examination, cycling exercise test and echo-Doppler examination

Leg complaints at maximal exercise in endurance athletes may have many causes, including arterial flow limitations in the iliac arteries. Such flow limitations can evolve into serious health problems due to increasing intravascular obstruction or even complete obstruction as a result of dissection or thrombosis. Early detection is therefore of clinical importance, but conventional diagnostic tools often prove inadequate. In the current study simple sports-specific tests are examined for their diagnostic power. Test variables derived from patient history, physical examination, cycling exercise testing followed by arterial pressure measurements at the ankle, and echo-Doppler examination with provocative manoeuvres were tested in 92 symptomatic legs (80 patients). A validated clinical classification acted as a reference. Several test variables proved useful. However, no single test variable combined a high sensitivity with a high specificity. Multivariate testing resulted in the correct classification of 91 % of patients, reaching a sensitivity of 0.90 and specificity of 0.93 (kappa 0.76). Four patients wrongly classified as non-vascular suffered from kinking in the common iliac artery that could not be visualised using the diagnostic tools currently available in this study.

IN CONCLUSION

simple sports-specific tests accurately diagnose iliac artery obstruction in endurance athletes.

Detection and treatment of claudication due to functional iliac obstruction in top endurance athletes: a prospective study

BACKGROUND

Endurance athletes often have restrictions in flow in their iliac arteries during exercise. Such restrictions have previously been ascribed solely to intravascular lesions. We postulate that flow could also be restricted by functional kinking in the arteries, and that surgical release of these kinks might be an effective treatment.

METHODS

We prospectively studied 80 endurance athletes who had complaints suggestive of flow restriction in the iliac arteries of one (n=74) or both (6) legs (total 92 legs). Using vascular diagnostic tools, we examined athletes while they were doing activities that often provoke flow restrictions. Restrictions were determined by measurement of systolic pressure in the ankle after exercise; peak systolic velocities were measured with echo-doppler. Kinks were detected with echo-doppler and magnetic-resonance angiography. When functional kinking was diagnosed as the cause of the restriction, the athlete was offered surgery to release the iliac arteries, as part of our prospective study.

FINDINGS

We recorded flow restrictions in the iliac arteries of 58 of 92 (63%) legs. In 40 of these legs (69%), kinks were the most important cause of the restriction, making these legs suitable for surgical release. We operated on 23 of 58 (40%) legs. All athletes who had an operation subjectively improved. Maximum workload in a cycling test and ankle pressure significantly improved after the operation. 20 (87%) athletes were able to successfully return to their desired high level of competition.

INTERPRETATION

Our sports-specific protocol is effective in detecting kinking of the iliac arteries as a cause for flow restriction in athletes who have few intravascular abnormalities when investigated with conventional vascular diagnostic tools. Surgical treatment directed at the kinking was less invasive and therefore a better alternative to vascular reconstruction in these athletes.

Color Doppler used to detect kinking and intravascular lesions in the iliac arteries in endurance athletes with claudication

OBJECTIVE

In endurance athletes, flow limitations in the iliac arteries are commonly ascribed to mechanically induced intravascular lesions (endofibrosis). We hypothesize that kinking of the vessels, occurring during exercise, can also cause such flow limitations. Conventional diagnostic tests fail to demonstrate such kinking.

METHODS

In the current study, the iliac arteries were examined in 50 endurance athletes suffering from flow limitations in the iliac arteries with color Doppler using provocative maneuvers of hip flexion, isometric psoas contraction and exercise. Five had both-sided complaints resulting in 55 symptomatic legs and 45 asymptomatic legs. Sixteen national level competitive cyclists served as control subjects resulting in 32 healthy reference legs.

RESULTS

The iliac arteries could be visualized accurately in 127/132 (96%) of the legs. The legs with insufficient image quality were not scored in the further analysis. In the external iliac artery, kinks were detected in 21/54 symptomatic legs (39%) compared to none in 28 reference legs. Intravascular lesions could be detected in 33/54 symptomatic legs (61%) compared to only 1/28 reference legs (4%). In the symptomatic legs Doppler measurements showed significantly higher peak systolic velocities in all test conditions compared to the reference legs (P<0.05). These differences increased significantly with provocative maneuvers (P<0.05).In the common iliac artery, kinks were demonstrated in 3/54 symptomatic legs (6%) and an intravascular lesion in 2/54 symptomatic legs (4%) only. Neither kink nor intravascular lesions were demonstrated in the reference legs. Peak systolic velocity measurements in the common iliac artery were in line with these observations and did not show differences between symptomatic and reference legs. The incidence of intravascular lesions in the external and common iliac artery is as expected, however, the incidence of kinks in the common iliac artery is much lower than reported from magnetic resonance angiography. This discrepancy is most probably caused by the fact that kinks in the common iliac artery are predominantly situated in the coronal plane, which cannot be visualized by color Doppler.

CONCLUSION

Both kinks and intravascular lesions are associated with flow limitations in the iliac arteries in endurance athletes. Color Doppler appears to be an effective technique to visualize and scale kinks and intravascular lesions in the external iliac artery and to visualize and scale intravascular lesions in the common iliac artery.

Magnetic resonance angiography used to detect kinking in the iliac arteries in endurance athletes with claudication

In endurance athletes, leg complaints upon maximal exercise caused by flow limitations in the iliac arteries are frequently encountered. We theorize that functional kinking of the vessels, which occurs especially during hip flexion, may be a cause for such flow limitations. Conventional diagnostic tests cannot demonstrate such kinkings. Using gadolinium-enhanced magnetic resonance angiography, a 3D dataset of the aorto-iliac arteries could be obtained with the hips flexed. An image processing procedure was developed using a new segmentation algorithm to be able to use standard surface rendering techniques to visualize the arteries with an improved 3D appearance. These techniques were applied in the current study in 42 endurance athletes with documented flow limitations in the iliac arteries. As a control group 16 national level competitive cyclists without flow limitations in the iliac arteries were studied. Forty-six affected legs were examined in 42 patients. In all patients and reference persons image quality was adequate and the segmentation algorithm could be applied. In 22 affected legs (48%) a kinking in the common iliac artery could be demonstrated, compared with one leg (3%) in the control group. In 13 affected legs (28%) a kinking in the external iliac artery could be demonstrated, compared with three legs (9%) in the control group. It can be concluded that flow limitations in the iliac arteries in endurance athletes are associated with kinkings in the common and/or the external iliac arteries. Magnetic resonance angiography with the hips flexed followed by this newly developed segmentation algorithm is effective to visualize and score these kinkings.

[Long-term intensive athletic training; few adverse effects on later physical health]

In general, physical activity benefits health. However, long-term intensive physical training may have detrimental effects on the health of some individuals. In cyclists, changes in the femoral arteries may occur leading to stenoses that are manifested in claudication type symptoms. Some endurance athletes may experience atrial fibrillations that are possibly related to long-term physical training. Older athletes only have an increased risk of osteoarthritis in joints that have suffered injuries. Menstrual disturbances and premature osteoporosis may occur in women as a consequence of intensive physical training. However, the risk for these adverse consequences of long-term physical training is small.

Flow limitations in the iliac arteries in endurance athletes. Current knowledge and directions for the future

Pain and powerless feeling in the leg during cycling may indicate a serious problem that limits the performance in cyclists. Apart from the well-known muscular and neurological origin, such complaints can also be attributed to flow limitations in the iliac arteries caused by functional lesions (kinking and/or excessive length of vessels) and/or intravascular lesions (endofibrosis). Reliable insight in the prevalence is lacking. Most intravascular lesions (approximately 90%) are located in the external iliac artery. The diagnosis is frequently missed because physiotherapists and medical doctors are often unacquainted with the problem. The only finding in physical examination, discriminating for a vascular problem, is a bruit in the inguinal region with the thigh maximally flexed. Available diagnostic techniques are proven to be inadequate for this specific lesion, which has characteristics other than those of atherosclerotic lesions. Moreover, common techniques in a vascular laboratory do not incorporate the specific sport conditions necessary for provoking the complaints. Provocative testing on a bicycle ergometer with high intensity of exercise, combined with postexercise blood pressure measurements (at the ankle of both legs, or the ankle to arm pressure ratio) is used. Imaging techniques (echo-doppler, arterial digital subtraction angiography, magnetic resonance imaging and angiography) are necessary for proper classification of the problem. The application of specific provoking manoeuvres (hip flexion, psoas contraction, high-intensity exercise) in combination with these imaging techniques prove to be potentially valuable, although the diagnostic accuracy has to be established. Treatment should be tailored to the specific problems of the individual patient. Conservative treatment mainly indicates an advice to change sports activity. Surgical mobilization of the iliac arteries for functional lesions, and vascular reconstructions in case of intravascular lesions are possible, although long-term follow-up is lacking. Percutaneous transluminal angioplasty and intravascular stent are contra-indicated because of high risks for dissection and reactive intimal hyperplasia, respectively.

Adding once-daily omeprazole 20 mg to metronidazole/amoxicillin treatment for Helicobacter pylori gastritis: a randomized, double-blind trial showing the importance of metronidazole resistance

OBJECTIVE

We compared the Helicobacter pylori eradication rate after a 14-day treatment with amoxicillin 500 mg t.i.d. and metronidazole 500 mg t.i.d. with or without omeprazole 20 mg once daily.

METHODS

This was a randomized, controlled trial in which omeprazole was given in double-blind fashion. Patients with H. pylori-associated gastritis were enrolled in four centers in Canada from July 1991 to January 1994. Eradication of H. pylori was assessed by histological evaluation and culture of endoscopic biopsies obtained from the antrum and corpus of the stomach.

RESULTS

The H. pylori eradication rate was 73% (33 of 45) in the omeprazole-amoxicillin-metronidazole group, compared with 66% (31 of 47) in the amoxicillin-metronidazole group. This 7% difference was not statistically significant (p = 0.43, 95% confidence interval for difference -11% to 26%). Metronidazole primary resistance in the prestudy cultures was found more frequently in the omeprazole-amoxicillin-metronidazole group than in the amoxicillin-metronidazole group. Resistance to metronidazole was an important predictor of treatment failure. The H. pylori eradication rate was 61% (19 of 31) for patients infected with metronidazole-resistant H. pylori strains, compared with 91% (30 of 33) eradication for those infected with metronidazole-sensitive strains (p < 0.01). Vaginal candidiasis was reported in four patients.

CONCLUSIONS

The H. pylori eradication rate was higher (73%) for omeprazole-amoxicillin-metronidazole than for the dual antibiotic therapy given without omeprazole (66%); however, this difference was not statistically significant. Metronidazole resistance significantly reduces H. pylori eradication rates.

The plasma lactate response to exercise and endurance performance: relationships in elite triathletes

The lactate response to exercise has been studied thoroughly during the last decades and it has been described using a variety of terms and definitions. Numerous investigations observed close relationships between the lactate response and endurance performance. The main question in this study was which of the various lactate responses during incremental exercise described in the literature was the best indicator of endurance performance. The plasma lactate response (PLR) was assessed during an incremental exercise test on 13 male elite triathletes (age 25.5+/-5.8 yrs; HT 179.7+/-5.4 cm; WT 71.3+/-4.7 kg) on a bicycle ergometer. The load was started at 2.5 W/kg and increased by 40 W every 4 min. We evaluated the following PLR-parameters: the workloads at the fixed lactate levels of 2, 3, 4, 5, 6, 7, and 8 mmol/l which were assessed by extrapolation from a workload-lactate-heart rate curve (P2, P3, P4, P5, P6, P7, P8 respectively), the lactate threshold which was defined as the workload at the point at which a non-linear increase of blood lactate occurred (Plt), and the workload at the lactate level that was 1 mmol/l above the baseline (P + 1). Four to seven weeks after the laboratory test, heart rate and lactate levels were assessed during a 40-km long time trial on a bicycle. Two parameters were considered as indicative of athletic performance: the road racing time (Tt), and the workload extrapolated from the workload-lactate-heart rate curve at the heart rate and lactate levels observed during the time trial (Pt). Only P2 showed a significant correlation with Tt (r=-0.65; p < 0.05; se = 72.5 s). Multiple regression analysis with the anthropometric parameters height and weight as additional independent parameters did not change the predictive value. We concluded that for predicting the cycling performance of similarly well-trained subjects the predictive value of PLR is negligible.

The maximal lactate steady state in elite endurance athletes

The upper limit of blood lactate resulting in a lactate steady state during prolonged exercise is called the maximal lactate steady state (MLSS). The purpose of this study was to investigate the lactate response to steady-state exercise during a field test in elite endurance athletes. Plasma lactate levels were assessed in 13 elite triathletes and 13 elite cyclists (mean +/- SD; age 23.7 +/- 5.1 yr; HT 180.2 +/- 6.3 cm; WT 70.3 +/- 5.9 kg; VO2 max 68 +/- 3.7 ml/min/kg) during a 40 km-long time trial on a bicycle (4 km course x 10 laps). The steady state was demonstrated by monitoring the heart rate and timing every course run. The lactate levels were expected to correspond to MLSS. The mean level of lactate during the time trial was 7.4 +/- 2.5 mmol/l. Five athletes maintained plasma lactate levels which exceeded 10 mmol/l or more for almost 1 h. The large value of individual variability was conspicuous (range 3.2-12.2 mmol/l). These values exceeded all previous reported levels for MLSS from other investigators. Our observations are important in sport medical practice since the different lactate responses to exercise are used as parameters in training management.

Hemorheological response to prolonged exercise--no effects of different kinds of feedings

Thirty-one male triathletes performed three experimental trials at one week intervals, with either a semi-solid or liquid carbohydrate feeding, or a liquid placebo. Exercise consisted of three hours of alternately cycling, running, cycling, and running at 75% VO2 max. Venous blood samples were taken before and immediately after the exercise. Viscometry was performed with a Contraves LS-30 viscometer and erythrocyte deformability was measured with the LORCA, a laser diffractometric system. Exercise caused a significant increase in whole blood and plasma viscosity, hematocrit, and osmolality, and a very small, but significant decrease in erythrocyte deformability, irrespective of the feedings consumed. Changes were not related to exercise performance, as defined by the maximal test time, probably due to a large fluid intake. The intake of different amounts of carbohydrate had no influence on the hemorheological parameters, probably since water content was equal among feedings. Erythrocyte deformability changes were small in comparison with the other hemorheological changes and a correlation between erythrocyte deformability and other parameters was absent. This may be due to erythrocyte properties to counterbalance volume shifts to ensure an optimal oxygen delivery in the microcirculation.

Hydrogen breath test as a simple noninvasive method for evaluation of carbohydrate malabsorption during exercise

The aim of this study was to examine hydrogen (H2) production with the hydrogen breath test (HBT) after ingesting primarily digestible carbohydrate (CHO) during 3 h of 75% maximal oxygen consumption exercise. This was done to indicate CHO overflow in the colon which may occur when gastric emptying, intestinal transit and CHO absorption are not matched and CHO accumulates in the colon where it is subject to bacterial degradation. Further, this study was designed to assess breath H2 production as a function of the type of CHO ingested and the type of exercise. A group of 32 male triathletes performed three exercise trials at 1-week intervals with either a semisolid (S) intake, an equal energy fluid intake (F) or a fluid placebo (P). Each trial consisted of cycling (sessions 1 and 3) and running (sessions 2 and 4). The mixed-expired H2 concentrations in the resting and "recovery" periods (5 min after each session) did not change significantly in time and did not differ among intakes. There were also no significant differences in H2 concentrations between resting and "recovery" conditions. During exercise, H2 concentrations decreased three to six-fold in comparison to resting and recovery levels and differed among intakes (ANOVA; P < 0.05). The H2 concentrations were almost continuously lower with P than with F and S. The H2 concentrations were significantly higher during running than during cycling. During exercise, we found that CHO overflow could be compared among intakes and between exercise types by using the HBT, provided the influence of other factors on H2 excretion--ventilation and intestinal blood flow--was similar for each condition.