The purpose of this study was to verify physiological responses to constant-load (continuous) vs. variable-intensity (interval) during 14 weeks of aerobic exercise on active men. The hypothesis was that would be differences in physiological variables on distinct modes of execution performed on the treadmill over a period of 14 weeks of training.
Initially there were thirty five subjects, but due factors outside the present study, three individuals were excluded from the program. Two individuals during maximal exercise test (VO2) showed clinical impairment test being interrupted by the doctor and the third individual presented a plantar fasciitis in the early familiarization. Thirty two healthy and active males volunteered to participate in the study. All subjects exercised habitually, with at least 1 year experience aerobic training. The Human Ethics Committee of Rio de Janeiro Federal University approved this study (no 58659/02471312.8.0000.5257).The subjects performed a total of nine visits to the laboratory of the Brazilian Navy at City of Rio de Janeiro for physical tests on different days, except between visits I-II and VII-III. The interval between visits was one week between visits II-III-IV and VIII-IX, six weeks between the first day of training and visits V, four weeks between V-VI-VIII. All subjects from interval and continuous groups performed a total of 46 sessions of supervised running program.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
35
The present study was designed to compare the physiological effects between the two training regimes and the control group.The subjects from interval and continuous group performed others activities as resistance training, swimming or soccer. Those activities wasn't controlled by our study, but the individual didn't do physical activities at least 3 hours before started our running sessions. The control group simply performed their normal physical activities (resistance training, swimming or soccer). But, each 3 weeks we had a contact with control group to check about any injury or illness that could affect the final results. None were found.
CEFAN
Rio de Janeiro, Rio de Janeiro, Brazil
Relative Maximal Oxygen Uptake
The relative maximal oxygen uptake was taken by individual connected to a metabolic gas analyzer (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) through which the gas samples were collected and measured each 10 seconds during the test. The participants were submitted to a ramp protocol with an initial velocity of 8.0 km/h (0% of inclination), progressive increments, a final velocity of 18 km/h (2% de inclination). The duration was equal to 10 minutes or until voluntary exhaustion.
Time frame: Pre and post 14 weeks
Absolute Maximal Oxygen Uptake
The absolute maximal oxygen uptake was taken by individual connected to a metabolic gas analyzer (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) through which the gas samples were collected and measured each 10 seconds during the test. The participants were submitted to a ramp protocol with an initial velocity of 8.0 km/h (0% of inclination), progressive increments, a final velocity of 18 km/h (2% de inclination). The duration was equal to 10 minutes or until voluntary exhaustion.
Time frame: Pre and post 14 weeks
Total Time Reaching on Maximal Test (tVO2max)
The criterion for determining the total time reaching in maximal VO2 test was associated with the time immediately preceding heart rate shown a reduction of five or more beats.
Time frame: Pre and post 14 weeks/46 sessions of training
Heart Rate on Maximal Test
The HR was collected pre and post training on maximal VO2 test. Initially, with the individual on the treadmill (Inbrasport Master Super, Porto Alegre, Brazil), electrodes (Micromed) were placed at the manubrium, right and left iliac crest for measured heart rate (HR) (derivation CM5) and were connected to an electromyography equipment (Micromed®). HR values were visualized through Elite software (Micromed Biotechnology, Brasilia, Brazil).
Time frame: Pre and post 14 weeks at rest (5 min sitting; before start the test), during the test (to determine max), and 60s and 120s immediately after the end of the test (on sitting position)
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Blood Lactate Concentrations on Maximal Test
Capillary blood samples (25 µl) were obtained from the finger of each subject during all tests and the \[La\] were measured using an (Accutrend®Plus Roche Diagnostics Gesellschaft mit beschränkter Haftung , Mannheim, Germany). The measuring range was 0.8-22 millimole (mM). The sample is collecting (Accu-Chek® Softclix) and first applied to a coded yellow test strip (Accutrend Blood measure-Roche) with a reagent chemical substance. Blood was added to the strip by letting it drip from a finger; in accordance with the instrument's instructions. The finger never touched the strip's pad in order to exclude any possible interference due to the sweat. All \[La\] were collected by a single, experienced investigator.
Time frame: Pre and post 14 weeks/46sessions on rest (5 min sitting position; before start the test); 1-3-5 min immediately after the end of the test (on sitting position).
Body Mass (BM)
To measure body mass Filizola scales with a stadiometer was used.
Time frame: Body Mass was collected pre and post training
Rate of Perceived Exertion (RPE) on Maximal Test
The RPE was collected at maximal test (see description of test on outcome measure "Maximal Oxygen Uptake"). Relative to overall feelings were collected by Category Ratio Scale (CR10) during the last 15 s of each stage using the Borg category (0 - 10) scale. Instructions for RPE were that "0" corresponds to rest, and "9 - 10" corresponds to maximal exertion. This verbal procedure was explained before initiating exercise.
Time frame: Pre and post 14 weeks/46 sessions of training
Fat Mass (%)
The subjects underwent a set of anthropometric assessments, which followed the norms of the International Society for Advancement of Kinanthropometry. The fat mass was calculated by percentage using the equation proposed by Jackson and Pollock (1978) from seven skinfold measurement. To measure the skinfolds, a Sanny Professional Skinfold Caliper was used.
Time frame: Pre and post 14 weeks/46 sessions of training
Heart Rate on Submaximal Test
Submaximal tests were done at the same treadmill (Treadmill® TR9100HR, Life Fitness, USA) as training.Before the test, all subjects should be able to do it at moderate-high intensity. The test began with three minutes of progressive warm-up. During the first minute, the subject maintains a light level; during the second and third minutes of the warm-up, the intensity was moderate. Starting from the fourth minute, the subject should be able to maintain a velocity for the next seven to ten minutes. This load can be adjusted as required, through verbal communication between the subject and the evaluator. The test finishes at the end of 10 minutes.The test velocity should be clearly constant at the end of the test. Heart rate were monitored and recorded at the end of each minute, e.g. 10 seconds before ending each measured minute, and the last measurement were at the end of the 10 minutes. The objective of this procedure was to identify the HR values for training intensities.
Time frame: Pre; during (retest I 0-6weeks; retest II 0-10 weeks) and post 14 weeks/46sessions training: rest (5-min sitting; before start the test); maximal during the test (maxHRsub); 60s-120s immediately after the end of the test (on sitting position).
Blood Lactate on Submaximal Test
Capillary blood samples (25 µl) were obtained from the finger of each subject during all tests and the \[La\] were measured using an (Accutrend®Plus Roche Diagnostics Gesellschaft mit beschränkter Haftung , Mannheim, Germany). The measuring range was 0.8-22 mM. The sample is collecting (Accu-Chek® Softclix) and first applied to a coded yellow test strip (Accutrend Blood Measure-Roche) with a reagent chemical substance. Blood was added to the strip by letting it drip from a finger; in accordance with the instrument's instructions we never let the finger touch the strip's pad in order to exclude any possible interference due to the sweat.
Time frame: Pre; during (retest I 0-6weeks; retest II 0-10 weeks) and post 14 weeks/46 sessions training: rest (5-min sitting; before start the test); 1-3-5 minutes immediately after the end of the test (on sitting position).
Submaximal Velocity [Vsub]
Submaximal tests were done at the same treadmill (Treadmill® TR9100HR, Life Fitness, USA) as training.Before the test, all subjects should be able to do it at moderate-high intensity. The test began with three minutes of progressive warm-up. During the first minute, the subject maintains a light level; during the second and third minutes of the warm-up, the intensity was moderate. Starting from the fourth minute, the subject should be able to maintain a velocity for the next seven to ten minutes. This load can be adjusted as required, through verbal communication between the subject and the evaluator. The test finishes at the end of 10 minutes. The test velocity should be clearly constant at the end of the test. Values of velocity were monitored and recorded at the end of each minute, e.g. 10 seconds before ending each measured minute, and the last measurement were at the end of the 10 minutes. The objective of this procedure was to identify the value of that speed has stabilized.
Time frame: Pre; during (retest I 0-6weeks; retest II 0-10 weeks) and post 14 weeks/46sessions of training
Rate of Perceived Exertion (RPE) on Submaximal Test
The RPE was collected at submaximal test (see description of test on outcome measure "HR at submaximal test"). Relative to overall feelings were collected by Category Ratio Scale (CR10) during the last 15 s of each stage using the Borg category (0 - 10) scale. Instructions for RPE were that "0" corresponds to rest, and "9 - 10" corresponds to maximal exertion. This verbal procedure was explained before initiating exercise.
Time frame: Pre; during (retest I 0-6weeks; retest II 0-10 weeks) and post 14 weeks/46sessions training