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Physiological Adaptations to Concurrent Endurance Training and Low Velocity Resistance Training G. J. Bell, S. R. Petersen, J. Wessel, K. Bagnall2 , H. A. Quinney Department of Physical Education and Sport Studies, 'Department of Physical Therapy and 2Department of Anatomy and Cell Biology, University of Alberta, Edmonton, Alberta. T6G 2H9

G. J. Bell, S. R. Petersen, J. Wessel, K. Bagnall

and H. A. Quinney, Physiological Adaptations to Concur-

rent Endurance Training and Low Velocity Resistance Training. Tnt J Sports Med, Vol 12, No 4, pp 384—390, 1991.

Accepted: October 4, 1990

This study investigated the effects of concurrent endurance and low velocity resistance training (LVR) on measures of strength and aerobic endurance. One group

(ES) performed concurrent endurance training 3 days a week and LVR training on alternate days, 3 days a week for 12 weeks. The other group (5) performed only LVR training 3 days a week for 12 weeks without any endurance training. Measurements and increases in training volume were made every three weeks in both groups. Group ES exhibited increases in submaximal exercise responses after 3, 9 and 12

weeks (p < 0.05). Knee extension peak torque and total work as well as cross-sectional area of quadriceps femoris were significantly increased after 6 and 9 weeks of training in both groups. These findings indicate that no significant differences in strength gains were observed between subjects performing concurrent endurance and resistance training or resistance training only. However, the time-course of adaptations between groups was somewhat different. Key word

Peak torque, total work, cross-sectional area, maximal oxygen consumption, submaximal exercise

Introduction

Hickson (20) reported that initially untrained

subjects performing concurrent endurance and high-resistance training exhibited a lack of strength (1 RM) gains after seven weeks of training followed by a slight decrease during 9 and 10 weeks of training. Maximal oxygen consumption was

not compromised and showed continual improvements throughout training. These findings led to the suggestion that

Int.J.SportsMed. 12(1991)384—390 GeorgThieme Verlag StuttgartNew York

formed simultaneously with high-resistance training. Further support for the interference effect was provided by Dudley and Djamil (9), who reported a compromise in knee extension peak torque at fast, but not slow, angular velocities after seven weeks of simultaneous endurance and velocity-controlled resistance training at a fast angular velocity. Also, Hunter et al.

(23) found that strength (1 RM) began to decline after 10 weeks of combined high-resistance and endurance training. These latter two studies (9, 23) also found no compromise in

maximal oxygen consumption with concurrent endurance and resistance training. Finally, Sale et al. (36) found that resistance and endurance training performed on the same day impeded strength development when compared to training for either on separate days. Contrary to the support for the existence of an interference phenomenon are other studies that have shown no compromise in strength gains with concurrent training (30, 37). Nelson et al. (30) reported that peak torque increases were similar with concurrent endurance and velocity-controlled resistance training at a slow velocity and resistance training only.

Both the concurrent training group and resistance training only group showed similar hypertrophy of muscle fibres after 20 weeks (30). Sale et al. (37), using a single-leg training model,

concluded that combined endurance and high resistance train-

ing does not impair the cellular adaptations or strength performance associated with training for strength or endurance separately. Thus, there seems to be some controversy re-

garding the adaptations to concurrent endurance and resistance training, which may be due to differences in training programs, experimental design and the lack of a clear timecourse assessment of dependent variables. Furthermore, all previous studies used untrained subjects and the positive or negative physiological adaptations of a trained group to concurrent resistance and strength training is unclear and warrants further investigation, particularly since this type of training is common to many athletes.

Therefore, the purpose of this study was to investigate the effect of concurrent endurance and velocity-con-

trolled resistance training at a slow velocity and resistance training only on strength adaptations using a trained group of subjects. Since all previous investigations have not shown an antagonism in aerobic endurance adaptations, this was not a specific purpose of this study.

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Abstract

an "interference effect" had occurred which restricted the development of strength when endurance training was per-

PhysiologicalAdaptations to Concurrent Endurance Training andLow VelocityResistance Training

Height (cm)

Weight

Group

Age (yrs)

ES S

25 (3.6) 22 (1.9)

178.4 (7.2) 178.5 (6.3)

77.2 (9.4) 78.4 (8.1)

(kg)

Mean values are indicated with SD in parentheses.

Methods

Subjects and ExperimentalDesign Thirty-one volunteers signed informed consent and agreed to participate in this research project. Subject characteristics are outlined in Table 1. All subjects were given a complete explanation of the testing protocols and training program during an orientation session. A quasi-experimental time-series design was chosen which allows periodic measurements and the introduction of an experimental change into this time-series of measurements (5). This design was chosen as it is

difficult to convince athletic and/or active populations to act as controls for extended periods without training, it allows an evaluation of the stability of the dependent measurements to be made prior to training and indicates whether the subjects

open circuit spirometry. Ventilation and expiratory oxygen and carbon dioxide content were determined and analyzed every 30 seconds with a Beckman Metabolic Measurement Cart (MMC). Calibration of the MMC for volume of air, temperature and barometric pressure was conducted before each testing session and the gas analyzers were calibrated before and after each test with gases of known concentration. Heart rate was recorded during the last 15 s of each minute from an electrocardiograph (ECG, Cambridge model VS4). The submaximal test consisted of six minutes of continuous rowing exercise at a power output of 125 W by maintaining flywheel revolution at 500 revolutions per minute against a resistance of 14.7 N (stroke rate of 24 to 26 strokes per minute maintained with a stroke rate watch). Pilot testing revealed a plateau in oxygen consumption and heart rate to occur for all subjects using this protocol. A small blood sample (approximately 1 ml) was taken from an antecubital vein precisely one minute after cessation of the submaxirnal test and 0.5 ml was deproteinized in 4% perchloric acid, centrifuged for ten minutes at 3000 xg and the supernatant drawn off for the spectrophotometric determination of venous lactate concentration (39). No changes in resting blood lactate levels or hernatocrit were observed during training.

were at a steady-state level of performance.

The subjects subsequently resumed rowing The volunteers consisted of individuals who had some previous experience with either both endurance and resistance training or resistance training only. Thus, group ES consisted of sixteen male subjects from the University of Alberta Rowing Club and undertook 12 weeks of concurrent endurance and low velocity resistance (LVR) training. The training experience of this group ranged from one to several years

of involvement in the sport of rowing at a provincial and national level. Fifteen male subjects from the University of Al-

berta who had some previous resistance training experience formed group S and performed only the LVR training program. The experience of this group ranged from one to several years of resistance training at least twice per week for 8 months of the year. Two subjects from group ES and one subject from

group S did not complete the training program due to health reasons not associated with the study resulting in a sample size of fourteen in each group. The subjects were tested on all dependent variables 4 weeks before training to serve as a control period, twice immediately prior to training (separate days) to determine test-retest reliability for all measurements and at 3week intervals during training. All subjects received one day rest prior to each testing session and were asked to refrain completely from any other training except that outlined by researchers.

Testing Procedures Indices of aerobic endurance were assessed in group ES to determine the effects of the endurance training program. No endurance measures were obtained from group S as it was not a specific aim of this study to determine the effect of resistance training on endurance adaptations.

Submaximal responses to an absolute workload and maximal oxygen consumption (VO2max) were assessed in group ES during an incremental test to fatigue on a rowing ergometer (Gjessing Ergorow, Bergen, Norway) using

after the submaximal portion of the test at a power output of 143 W and the resistance was increased by 2.5 N every minute for 6 minutes. During the final two workloads, the resistance was also increased by 2.5 N, but the subjects were requested to increase stroke rate and flywheel revolutions to a maximum. The subjects were verbally encouraged to continue this maximal rate beyond eight minutes if possible. However, no subject was able to continue past 10 minutes. The main criterion used for determining achievement of VO2rnax was a peak or plateau in oxygen consumption with an increase in power output. Secondary criteria included: reaching age-predicted or known maximum heart rate, exceeding a respiratory exchange ratio of 1.5, or until volitional exhaustion occurred (42). Test-retest reliability (intraclass correlation coefficients) for VO2max, maximum heart rate and submaximal heart rate, blood lactate and oxygen consumption were 0.96, 0.99, 0.89, 0.91 and 0.99, respectively.

Strength of the right knee extensors was assessed in both groups ES and S as the highest point on the torque vs angle curve (peak torque of a single knee extension) and total work during four maximal knee extensions at an a calibrated Kinetic Comangular velocity of 1.05 rad s municator (Kin Corn) isokinetic dynamometer (gravity compensated). The validity and reliability of the Kin Corn dynamometer has previously been established (12). The testing mode was concentric for both knee extension and knee flexion. Only knee extension was reported for this study as it was emphasized during resistance training and is a major joint movement in rowing exercise. Furthermore, most studies that involved concurrent endurance and resistance training report data frorn the lower limb (9, 20, 23, 36). The subject set-up and

testing protocol used in this study has previously been described (2). Test-retest reliability (intraclass correlation coefficients) for peak torque and total work were 0.98 and 0.98, respectively.

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Table I Subject characteristics

mt. i Sports Med. 12 (1991) 385

mt. J. Sports Med. 12(1991)

Cross-sectional area (CSA) of the quadriceps femoris muscle was determined using computerized tomogra-

phy (CT) scanning (Model 9800, General Electric Medical Systems). Previous research has suggested that this technique is sensitive to changes in muscle size with training (21, 27). Both groups underwent CT scans immediately prior to training and after 6, 9 and 12 weeks of training. Scans were not taken during the control phase or after 3 weeks of training to reduce the amount of radiation exposure. Previous research in our laboratory has shown no change in CSA of the quadriceps femoris muscle prior to training using a similar sample of subjects (93.2 cm2 before vs 93.0 cm2 after a 5-week control per-

iod) and intra-rater reliability of the analysis of CSA and of landmarking was 0.99 and 0.98, respectively (2). The scan site

was at a point halfway between the crest of the greater trochanter and the knee joint space. A small line (1.5 cm long) was

drawn on the skin with an indelible marker and this line was

periodically remarked during the study. The site was remeasured prior to every scan to ensure accuracy. The subjects were supine during scanning, with their arms at the side and their feet approximately 15 cm apart, which allowed some clearance (2 to 3 cm) between the right and left thigh. Both thighs were visually positioned parallel to the scanning platform using foam wedges under the hips, calves and ankles to ensure that the scan was taken perpendicular to the thighs. Black and white contact prints of the radiographic images were taken and the boundary of the quadriceps femoris muscle group was outlined prior to computer analysis of CSA on the General Electric 9800 computer planimetry system. All analyses were conducted by the same investigator.

Training Program The endurance training program for group ES involved continuous rowing exercise 3 days per week (Monday, Wednesday, Friday) on rowing exercise machines (Concept II) at an intensity equivalent to 85 to 90% of maximum heart rate (approximately 75% VO2max). This type of endurance training was chosen as it was typical of an off-season program for the oarsmen involved in this study. Individual heart rates were monitored each session by the subjects using Sport Tester portable heart rate monitors (Polar Electro Ltd.). The accuracy of these monitors has previously been reported (26). Duration of training was initially 40 minutes and was progressively increased by 5 minutes every three weeks until 55

minutes of training was achieved. All training sessions were supervised.

Low velocity resistance (LVR) training was

performed on variable resistance hydraulic equipment (Hydra-Fitness Industries, Sherwood Park, Alberta) 3 times per week (Tuesday, Thursday, Saturday) for 12 weeks on different days than endurance training for group ES. Group S completed 3 resistance training sessions a week (Monday, Wednesday, Friday) for 12 weeks and these subjects were allowed one endurance training session (continuous exercise at a moderate intensity for a maximum of 30 minutes) per week in

an attempt to maintain aerobic fitness as these subjects were active prior to this study. The resistance training velocity was approximately 1.05 rads Since the hydraulic cylinders do not provide a true isokinetic loading system, average angular velocity was approximated from the range of motion and the number of repetitions performed in a fixed time period. For

G. J. Bell, S. R. Petersen, J. Wessel, K. Bagnall, H. A. Quinney Table 2 Absolute and relative VO2max and maximal heart rate (HRmax) for group ES 4 weeks before (—4) and just prior to (6 and 3 days before) training and after 3, 6,9 and l2weeks of training VO2max HRmax

—4weeks —6 days

—3days

3 weeks 6 weeks 9 weeks 12 weeks

(1mm —

(mlkg 1min ) (bmin )

3.87 (.36) 3.93 (.38) 4.00 (.41)c

50.6 (5.6) 50.8 (5.5) 51.7 (5.1)c

190 (5) 189 (9) 191 (8)

4.18 (39)a 4.29 (39)ab

53.9 (5.0)a

555 (55)ab

187 (6)d 188 (8)

4.30 (39)ab 4.31 (36)ab

55.5 (s3)b

189 (7)

55.7 (45)ab

187 (7)d

a = significantly different from all scores before training, p

Physiological adaptations to concurrent endurance training and low velocity resistance training.

This study investigated the effects of concurrent endurances and low velocity resistance training (LVR) on measures of strength and aerobic endurance...
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