Showing papers on "Interval training published in 1997"

Interval training in patients with severe chronic heart failure: analysis and recommendations for exercise procedures.

Abstract: This study analyzes a new exercise training procedure, which includes interval exercise training on cycle ergometer (IntCT) (30-s work phases/60-s recovery phases) and on treadmill (60-s work and recovery phases each). Training was applied for 3 wk in 18 patients with severe chronic heart failure (CHF) ((mean +/- SEM) age 52 +/- 2 yr, ejection fraction 21 +/- 1%). Peak VO2 was increased from 12.2 +/- 0.7 to 14.6 +/- 0.7 ml-kg-1 min-1 owing to training (P 172 +/- 10 W-->200 +/- 11 W; P 86 +/- 6 W-->100 +/- 7 W; P < 0.001). Physical responses to IntCT were measured. There was no significant change in heart rate, blood pressure, and ratings of perceived exertion (RPE) using a Borg Scale between the first and the third week of training (heart rate 88 +/- 3 b.min-1; blood pressure 115 +/- 4/80 +/- 2 mm Hg; leg fatigue 12 +/- 1; dyspnea 10 +/- 1). Mean lactate concentration (1.70 +/- 0.09 mmol-1-1) indicated an overall aerobic range of training intensity. When compared with the commonly used intensity level of 75% peak VO2 from an ordinary ramp test (work rate increments 12.5 W.min-1), the performed training work rate was more than doubled (240%; P < 0.0001) while cardiac stress was lower (86%; P < 0.01). Values of norepinephrine and epinephrine as well as of RPE corresponded to those measured at 75% peak VO2. Interval exercise training is thus recommended for selected patients with CHF as it allows intense exercise stimuli on peripheral muscles with minimal cardiac strain. Using a steep ramp test, training work rate can be determined and readjusted weekly during initial training period.

Creatine and phosphocreatine: a review of their use in exercise and sport.

Abstract: Objective: Creatine and phosphocreatine (PCr) are important compounds in the normal energy metabolism of muscle. Recently, it has been shown that dietary creatine (5 to 20 g/day) can increase muscle creatine and PCr, with enhancement in anaerobic exercise performance after two weeks of administration caused by an increase in anaerobic capacity. Data Sources: MEDLINE was searched from 1983 to 1996 using key word “creatine” along with “humans,” “muscle,” “exercise,” and “transport.” Also, APStracts, the American Physiology Society search engine for abstracts, was searched from 1994 to 1996. Data Synthesis: Creatine is transported into the muscle cell by a specific transporter, resulting in increased intracellular creatine and PCr. The PCr is capable of acting as an energy buffer, protecting the adenosine triphosphate (ATP) concentration. Maintaining muscle nucleotides therefore enhances exercise performance and recovery. There have been reports that PCr protects the cells from ischemic damage and decreases the loss of nucleotides by stabilizing cell membranes. Indeed, intravenous PCr (2-4 g/day) has been administered to cyclists, resulting in a faster recovery time between training sessions. Conclusions/Recommendations: It is becoming evident that oral creatine supplementation may yield certain benefits to enhance the athlete's performance during maximal anaerobic exercise and interval training.

Influence of exercise-induced plasma volume changes on the interpretation of biochemical data following high-intensity exercise

Abstract: OBJECTIVE To assess the effects that exercise-induced plasma volume changes (PVCs) have on the interpretation of biochemical and hormonal parameters in the blood of athletes after high-intensity exercise. It was hypothesized that two unrelated high-intensity exercise protocols, performed by two separate subject groups each using different exercise modes, would result in similar percentage changes in plasma volume (% delta PV). It was further hypothesized that the % delta PV, measured in both protocols, would comparably influence the interpretation of biochemical variables measured following exercise. DESIGN An experimental before-after trial on volunteers was performed. Two different exercise modes employing two different high-intensity acute exercise protocols were investigated. Eight male swimmers performed an interval training session (ITS) consisting of 15 x 100-m freestyle efforts at 95% of their maximal exercise intensity, and eight male runners performed a multistage discontinuous treadmill test (MSD) to volitional exhaustion. SETTING The Human Performance Laboratory at the Department of Human Movement at the University of Western Australia. MAIN OUTCOME MEASURES Blood samples obtained before, immediately after, and 30, 60, and 120 min during recovery were analyzed for plasma volume changes, urea, uric acid, creatinine, albumin, calcium, iron, transferrin, testosterone, cortisol, and sex hormone-binding globulin (SHBG). MAIN RESULTS The ITS and MSD protocols produced similar and significant alterations (p < 0.01) in plasma volume. Both protocols also elicited significant fluctuations (p < 0.01) in the concentration of most of the parameters measured (excluding iron). When albumin, transferrin, testosterone, and SHBG values were adjusted for the significant % delta PV, their concentrations did not change over the experimental period, suggesting that the changes in measured concentration of these parameters may be, in part, due to changes in plasma volume. However, urea, uric acid, creatinine, calcium, and cortisol, when corrected for % delta PVC, still demonstrated significant changes (p < 0.01). CONCLUSIONS It is recommended, when sampling biochemical and hormonal parameters in blood following an acute bout of exercise, that corrections for PVCs should be conducted. Apparent changes in blood solutes may reflect PVCs. PVCs should be taken into consideration when interpreting results regardless of exercise protocol and exercise mode performed.

Heart rate interval control for cardiopulmonary interval training

Abstract: Cardiopulmonary interval training between a user high target heart rate and a user low target heart rate is obtained with an exercise apparatus (10, 60) by increasing the load (130) of the exercise apparatus (10, 60) at a first predetermined rate until either the maximum machine load is obtained (134) or the high target heart rate (132). When this event occurs, the load can then be maintained (136) at a fixed level for a predetermined time. Thereafter, the load is decreased (138) until the low target heart rate is obtained (140), or the user-set exercise duration expired. The heart rate of the user is monitored during the exercise. In the event that measurement of a valid heart signal is lost at any time (140), any increase or decrease of the load of the exercise apparatus is terminated (142) until a valid heart rate signal is reacquired. In the case when an exercise apparatus is a treadmill (10), the load can be varied by increasing or decreasing both the speed adjustment and the elevation adjustment of the treadmill. In the preferred embodiment, the speed is first adjusted until a user-set maximum speed is obtained and thereafter the elevation is adjusted in order to obtain the load variations toward or from the high and low target heart rates. The exercise may be repeated between the low and high target heart rates to provide cardiopulmonary interval training.

Acute intensive interval training and in vitro t-lymphocyte function

Abstract: Five male endurance-trained runners completed an interval running session of 15 x 1-min intervals at 95% VO2 max. Venous blood samples were collected pre-exercise and then immediately, 30- and 60-minutes post-exercise. The response of cultures of total lymphocytes to mitogen (phytohaemagglutinin) were significantly reduced immediately after exercise, but returned to resting levels by 30-min of recovery. Conversely, the mitogen response of cultures of pure T-lymphocytes (CD4+ and CD8+ cells), separated using a magnetic separation technique, showed no significant change during the exercise and recovery periods. These data showed directly that there was no apparent change in the functional capability of T-lymphocytes following an intensive interval training session. Furthermore, there were significant changes in the composition of the total lymphocyte cultures immediately post-exercise; increased numbers of natural killer (NK) cells (CD56+) and T-suppressor cells (CD8+) and decreased numbers of T-helper cells (CD4+). There were also significant correlations between total mitogen response and the composition of the cultured lymphocytes. These data indicated that the large increases in NK cells, relative to T-cells, following intensive exercise, were the most likely cause of the reduced mitogen response of total lymphocyte cultures.

Monitoring high-intensity endurance training using neuromuscular excitability to recognize overtraining.

Abstract: The minimal rectangular current pulse that produces a single contraction of reference muscles at different pulse durations has been recommended as a marker of the neuromuscular excitability (NME) of skeletal muscles. NME is improved in well-trained, non-fatigued endurance athletes and deteriorates after prolonged heavy exercise and high-volume overtraining. The hypothesis was tested that a deterioration in NME also indicates an early stage in the overtraining process during high-intensity endurance training. Six subjects participated for 40-60 min per day in a 6-week, 6-days-per-week, intensive, steady-state and interval training program using a cycle ergometer. Training was stopped each day on volitional exhaustion. On day 7 of each week training was of low intensity for about 30-40 min. Submaximum and maximum power output were significantly increased after 3 weeks, but there was no further improvement, rather a deterioration after week 6 compared to week 3. Even after 2 weeks of regeneration no supercompensation was evident, rather a decrease in maximum power output. NME was slightly improved after 3 weeks, but deteriorated after 6 weeks, and was again normalized after 2 weeks of regeneration. The discrepancy between normalization of NME and still-deteriorated performance ability after 2 weeks of regeneration reflects additional significant, and probably central mechanisms that explain persistent performance incompetence. Deterioration in NME may indicate an early stage in the overtraining process during high-volume as well as high-intensity endurance overtraining, but normalization does not necessarily indicate sufficient regeneration.

Physiological response of 5/1 intermittent aerobic exercise and its relationship to 5 km endurance performance.

Abstract: A great number of specialists and coaches believe that conventional laboratory measurements lack specificity and that more practical testing should be instituted. The majority of studies have addressed this issue by looking at the relationship between physiological variables and time trials (TT). However, few have examined the pertinence of standardized aerobic interval training (AIT) programs to a simulated race performance or time trial. We studied 23 athletes (runners and multi-sport) to determine if their performance on the track during regular strenuous intermittent workouts would be associated with the 5000 m TT. The 3 interval track workouts each totalling 4800 m with a work to rest ratio of about 5 to 1, consisted of either 12 x 400 m (15 s rest), 6 x 800 m (30 s rest) or 3 x 1600 m (60 s rest) and performed at maximal cruising speed (maxCS). Correlation coefficients between the 400, 800, 1600 m workouts and 5000 m TT were not significantly higher (0.90, 0.95, 0.93) than those for VO2max (0.84) or maximal aerobic speed (0.85). When considering only the work interval, the mean %HRmax for the AIT and TT were accomplished respectively at 97.5 and 97.3 for the runners and 95.9 and 95.7 for the multi-sport athletes. In conclusion, our results indicate that the AIT programs performed with brief rest periods during normal training periods are as capable of predicting 5000 m race performance as are laboratory measurements. Also, within the limit of this study, the 6 x 800 m (30 s rest) AIT workout seems to be a very efficient and specific manner to simulate a competitive endurance performance.

The effect of water immersion on lactic acid kinetics during swimmimg interval training recovery periods

Abstract: The purpose of the study was to detennine the difference in the circulation of lactic acid following high intensity swimming, between resting immersed in water or resting sitting on the pool deck, completely out of the water. Six (four male and two female) collegiate swimmers volunteered for the study. The swimmers were randomly assigned to two groups and a counterbalance design was employed, where each group experienced both treatments (one resting out of the water, one resting in the water), in different orders. Each swimmer completed an identical warm-up and then swam five 100 yard swims at 8595% intensity, with one group resting three minutes between 100 yard swims sitting upright on the pool deck, and the other group remaining immersed in water for the three minute rest interval. Blood samples were taken during the second minute of the rest intervals, following the first, third and fifth swims. Analysis of the samples was conducted with a YSI 231 Lactate Analyzer. Results showed that the swimmers had higher levels of circulating lactic acid following the first swim when they remained in the water. All six swimmers then showed a rapid inflection of lactic acid levels between the first and third trail when out of the water for the rest intervals. Lactic acid levels showed only a slight increase when the swimmers remained in the water during rest. Results of the study showed a distinct difference in the circulatory patterns of lactic acid in swimmers following high intensity swimming between rest taken out of the water and in the water.