Effects of high-intensity interval training on trajectories of gas-exchange measures and blood lactate concentrations during cardiopulmonary exercise tests in cardiac rehabilitation-A randomized controlled trial.

BACKGROUND: The optimal allocation of training time to different intensities in cardiac rehabilitation is still under debate. The objective of this study was to explore whether in a 12-week cardiac rehabilitation program, replacement of two of four usual continuous endurance training (CET) sessions per week with energy expenditure-matched high-intensity interval training (HIIT) affects the trajectories of cardiopulmonary exercise test (CPET) variables such as ventilatory equivalents for O2 (EqO2 ) and CO2 (EqCO2 ), and blood lactate (BLa) during CPET. METHODS: Eighty-two male patients undergoing outpatient cardiac rehabilitation after an acute coronary syndrome were randomized to CET (age [mean ± SD] 61.7 ± 9.8 years, body mass index [BMI] 28.1 ± 3.4) or HIIT+CET (60.0 ± 9.4 years, BMI 28.5 ± 3.5). CPET was performed at baseline, after 6 and after 12 weeks. HIIT consisted of ten 60-s bouts of cycling at an intensity of 100% of the maximal power output (Pmax ) achieved in an incremental test to exhaustion, interspersed with 60 s at 20% Pmax . CET was performed at 60% Pmax with equal duration. Training intensities were adjusted after 6 weeks to account for the training-induced improvement in cardiorespiratory fitness. The entire functions defining the relationship between EqO2 , EqCO2 , and BLa, with power output were modeled using linear mixed models to assess how these trajectories are affected by HIIT. RESULTS: After 6 and 12 weeks, Pmax increased to 112.9% and 117.5% of baseline after CET, and to 113.9% and 124.7% after HIIT+CET (means). Twelve weeks of HIIT+CET elicited greater reductions of EqO2 and EqCO2 than CET alone (p < 0.0001 each) in a range above 100% baseline Pmax . Specifically, at 100% of baseline Pmax , least squares arithmetic mean EqO2 values of CET and HIIT+CET patients were 36.2 versus 33.5. At 115% and 130% of baseline Pmax , EqO2 values were 41.2 versus 37.1 and 47.2 versus 41.7. Similarly, corresponding EqCO2 values of CET and HIIT+CET patients were 32.4 versus 31.0, 34.3 versus 32.2, and 37.0 versus 34.0. Conversely, mean BLa levels (mM) were not differently affected (p = 0.64). At 100%, 115%, and 130% of baseline Pmax after 12 weeks, BLa levels did not differ to a relevant extent (least squares geometric means, 3.56 vs. 3.63, 5.59 vs. 5.61, 9.27 vs. 9.10). CONCLUSIONS: While HIIT+CET reduced ventilatory equivalents more effectively than CET alone, specifically when patients were approaching their maximal performance during CPET, both training strategies were equally effective in reducing BLa levels.

Outpatient cardiac rehabilitation: the Austrian model.

Over the past decades undisputable evidence has accumulated identifying the panoply of beneficial effects of exercise training, smoking cessation, blood pressure lowering, glycaemic and lipid control, as well as psycho-social interventions on cardiovascular risk factors, the well-being, morbidity and mortality of patients with cardiac diseases with or without acute events. Nevertheless, despite all the evidence, insurance companies are more than hesitant to provide patients with an adequate infrastructure to allow outpatient cardiac rehabilitation in their community. Whereas some countries still favour in-hospital rehabilitation, others are on the verge of introducing cardiac rehabilitation for the first time. Thanks to the efforts of the Working Group of Outpatient Cardiac Rehabilitation of the Austrian Cardiac Society, detailed guidelines for outpatient cardiac rehabilitation have been introduced, which not only include aims, contents and duration of outpatient cardiac rehabilitation, but also requirements for staff, quality of care and infrastructure. As a result cardiac rehabilitation in Austria is currently undergoing a transition process from exclusive in-hospital cardiac rehabilitation to a more open approach of granting patients a choice between in-hospital and outpatient rehabilitation. Experience gained appears relevant to a great number of colleagues in many countries Europe - as well as worldwide. Since these guidelines were and still are the basis for implementing outpatient cardiac rehabilitation, they are presented in great detail, so that they may either be applied as is or simply stimulate discussion.

A single nucleotide polymorphism associates with the response of muscle ATP synthesis to long-term exercise training in relatives of type 2 diabetic humans.

OBJECTIVE: Myocellular ATP synthesis (fATP) associates with insulin sensitivity in first-degree relatives of subjects with type 2 diabetes. Short-term endurance training can modify their fATP and insulin sensitivity. This study examines the effects of moderate long-term exercise using endurance or resistance training in this cohort. RESEARCH DESIGN AND METHODS: A randomized, parallel-group trial tested 16 glucose-tolerant nonobese relatives (8 subjects in the endurance training group and 8 subjects in the resistance training group) before and after 26 weeks of endurance or resistance training. Exercise performance was assessed from power output and oxygen uptake (VO(2)) during incremental tests and from maximal torque of knee flexors (MaxT(flex)) and extensors (MaxT(ext)) using isokinetic dynamometry. fATP and ectopic lipids were measured with (1)H/(31)P magnetic resonance spectroscopy. RESULTS: Endurance training increased power output and VO(2) by 44 and 30%, respectively (both P < 0.001), whereas resistance training increased MaxT(ext) and MaxT(flex) by 23 and 40%, respectively (both P < 0.001). Across all groups, insulin sensitivity (382 ± 90 vs. 389 ± 40 mL · min(-1) · m(-2)) and ectopic lipid contents were comparable after exercise training. However, 8 of 16 relatives had 26% greater fATP, increasing from 9.5 ± 2.3 to 11.9 ± 2.4 µmol · mL(-1) · m(-1) (P < 0.05). Six of eight responders were carriers of the G/G single nucleotide polymorphism rs540467 of the NDUFB6 gene (P = 0.019), which encodes a subunit of mitochondrial complex I. CONCLUSIONS: Moderate exercise training for 6 months does not necessarily improve insulin sensitivity but may increase ATP synthase flux. Genetic predisposition can modify the individual response of the ATP synthase flux independently of insulin sensitivity.

Early 4-week cardiac rehabilitation exercise training in elderly patients after heart surgery.

PURPOSE: The aim of this study was to assess the effects on exercise performance of supplementing a standard cardiac rehabilitation program with additional exercise programming compared to the standard cardiac rehabilitation program alone in elderly patients after heart surgery. METHODS: In this prospective, randomized controlled trial, 60 patients (32 men and 28 women, mean age 73.1 +/- 4.7 years) completed cardiac rehabilitation (initiated 12.2 +/- 4.9 days postsurgery). Subjects were assigned to either a control group (CG, standard cardiac rehabilitation program [n = 19]), or an intervention group (IG, additional walking [n = 19], or cycle ergometry training [n = 22]). A symptom limited cardiopulmonary exercise test and 6-minute walk test (6MWT) were performed before and after 4 weeks of cardiac rehabilitation. The MacNew questionnaire was used to assess quality of life (QOL). RESULTS: At baseline, no significant differences for peak oxygen uptake ((.)VO2), maximal power output, or the 6MWT were detected between IG and CG. Global QOL was significantly higher in IG. After 4 weeks of cardiac rehabilitation, patients significantly improved in absolute values of the cardiopulmonary exercise test, 6MWT, and QOL scores. Significant differences between groups were found for peak (.)VO2 (IG: 18.2 +/- 3.1 mL x kg x min vs. CG: 16.5 +/- 2.2 mL x kg x min, P < .05); maximal power output (IG: 72.2 +/- 16 W vs. CG: 60.7 +/- 15 W, P < .05); 6MWT (IG: 454.8 +/- 76.3 m vs. CG: 400.5 +/- 75.5 m, P < .05); and QOL global (IG: 6.5 +/- 0.5 vs. CG: 6.3 +/- 0.6, P < .05). CONCLUSION: The supplementation of additional walking or cycle exercise training to standard cardiac rehabilitation programming compared to standard cardiac rehabilitation alone in elderly patients after heart surgery leads to significantly better exercise tolerance.

Short-term exercise training does not stimulate skeletal muscle ATP synthesis in relatives of humans with type 2 diabetes.

OBJECTIVE: We tested the hypothesis that short-term exercise training improves hereditary insulin resistance by stimulating ATP synthesis and investigated associations with gene polymorphisms. RESEARCH DESIGN AND METHODS: We studied 24 nonobese first-degree relatives of type 2 diabetic patients and 12 control subjects at rest and 48 h after three bouts of exercise. In addition to measurements of oxygen uptake and insulin sensitivity (oral glucose tolerance test), ectopic lipids and mitochondrial ATP synthesis were assessed using(1)H and(31)P magnetic resonance spectroscopy, respectively. They were genotyped for polymorphisms in genes regulating mitochondrial function, PPARGC1A (rs8192678) and NDUFB6 (rs540467). RESULTS: Relatives had slightly lower (P = 0.012) insulin sensitivity than control subjects. In control subjects, ATP synthase flux rose by 18% (P = 0.0001), being 23% higher (P = 0.002) than that in relatives after exercise training. Relatives responding to exercise training with increased ATP synthesis (+19%, P = 0.009) showed improved insulin sensitivity (P = 0.009) compared with those whose insulin sensitivity did not improve. A polymorphism in the NDUFB6 gene from respiratory chain complex I related to ATP synthesis (P = 0.02) and insulin sensitivity response to exercise training (P = 0.05). ATP synthase flux correlated with O(2)uptake and insulin sensitivity. CONCLUSIONS: The ability of short-term exercise to stimulate ATP production distinguished individuals with improved insulin sensitivity from those whose insulin sensitivity did not improve. In addition, the NDUFB6 gene polymorphism appeared to modulate this adaptation. This finding suggests that genes involved in mitochondrial function contribute to the response of ATP synthesis to exercise training.

Respiratory gas exchange and lactate measures during competitive orienteering.

PURPOSE: In the past, orienteering sports analyses were based on heart rate (HR) and lactate (LA) measures. This study assessed additional respiratory gas exchange measures (RGEM) to provide further information regarding the physiological requirements of orienteering competitions (OTC). METHODS: Eleven elite male athletes performed simulated OTC. RGEM were performed using a portable system. LA was determined after each section (total of six) of OTC. Athletes were also subjected to treadmill testing (TT). RESULTS: Average values for the entire OTC were [OV0312]O(2OTC): 56.4 +/- 4.5 mL.kg-1.min-1 (83.0 +/- 3.8% of [OV0312]O(2max) of TT), HR(OTC): 172 +/- 11 bpm, and LA(OTC): 5.16 +/- 1.5 mmol.L-1. The highest measured [OV0312]O(2OTC) of an athlete in this study was 64.4 +/- 2.9 mL.kg-1.min-1. [OV0312]O(2OTC) was 94.6 +/- 5.2% of [OV0312]O(2IAT) (IAT= individual anaerobic threshold), HR(OTC) was 98.0 +/- 2.9% of HR(IAT), respiratory exchange ratio was 97 +/- 3.8% and LA(OTC) was 143.9 +/- 24.2% of LA(IAT). In contrast to [OV0312]O(2) and LA, average HR were similar in all sections of OTC despite topographical differences of the course. No correlations were found between running time of OTC and variables of endurance performance. Running time correlated with running distance (P < 0.001; r = 0.83) and running speed (r = 0.98; P < 0.001). CONCLUSION: 1) Energy requirements during OTC were derived predominately via aerobic metabolism. 2) The highest [OV0312]O(2OTC) value of 64.4 mL.kg-1.min-1 may be regarded as the reference for intensities of OTC. 3) During OTC, most athletes avoid high-intensity periods of long duration. 4) Performance in OTC was essentially influenced by technical abilities. 5) Using only LA for evaluation may lead to overestimation of energy demands during OTC. 6) HR measures were not sufficiently sensitive to ascertain energy requirements of the OTC. Therefore, RGEM provided additional information regarding energy expenditure of OTC compared with LA and HR measures alone.

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles.

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (VO(2)max): 57.3 (5.1) ml.kg(-1).min(-1)] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; VO(2)max: 67.9 (3.8) ml.kg(-1).min(-1)] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average VO(2) was considerably lower [29.1 (5.6) ml(.)kg(-1.)min(-1)] or 51.1 (10.9)% of VO(2)max and 64.8.0 (13.3)% of VO(2) determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol.l(-1)]. The highest average VO(2 )value for a whole game was 47.8 ml.kg(-1.)min(-1) and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominantly via aerobic mechanism of energy delivery. During OTC, we found an average VO(2) of 56.4 (4.5) ml.kg(-1).min(-1) or 83.0 (3.8)% of VO(2)max and 94.6 (5.2)% of VO(2) at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol.l(-1)) although the average VO(2) was significantly lower than VO(2) at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of requirements of sports and assist in the optimization and interpretation of training in athletes.