By: John, Adam, and Andrew

Purpose The purpose of this study was to determine the effectiveness of brief intense interval training as exercise intervention for promoting health and to evaluate potential benefits about common interventions, that is, prolonged exercise and strength training Hypotheses: None

Sampling Participants 36 untrained men that have not participated in any sort of physical training for at least 2 years. Ages 20 – 43, all non-smokers. Assignment Divided into 4 groups (study doesn’t specify assignment type)

Groups Group 1 = intense interval running (INT) n = 8 Group 2 = strength training (STR) n = 8 Group 3 = prolonged “traditional” moderate-intensity running (MOD) n = 9 Group 4 = control group (COD) n = 11

Procedure Exercise Test: Pulmonary gas exchange, heart rate, and venous blood sampling were performed during a standardized treadmill test. Consisted of 6 min of walking at 6.5 km/h and 6 min of sub- maximal running at 9.5 km/h. Followed by a 15 min rest and thereafter an incremental test to exhaustion. Measurements were taken during the last 3 min of each 6 min period. VO2 (max) and HR (max) were determined as the peak value reached in a 30 sec period during the incremental test.

Procedure Subjects were familiarized with the exercise test and blood pressure measurements at least one time before the experiment. Fasting blood glucose, lipoproteins, resting HR, and blood pressure were determined in the morning under standardized conditions and after an overnight fast. Blood pressure was measured at least six times, with the subjects in a supine position, by an automatic upper arm blood pressure monitor. The average of the 6 measurements was recorded. (M-7 or HEM-709; OMRON, Schaumburg, IL),

Procedure Oral glucose tolerance test: Subjects refrained from performing any strenuous physical activity for 2 days before the OGTT and attended the laboratory after fasting overnight. Before OGTT, 2 mL of blood was drawn to determine fasting insulin and glucose levels. Also, 10 mL of blood was drawn to determine plasma fatty acid, HDL cholesterol, and plasma triacylglycerol concentrations. Muscle biopsies were taken under local anesthesia. Post-training biopsies were obtained 48 to 72 hours after the final training session.

Procedure Training: High intensity interval training (INT) Attended sessions twice a week. Less than a 20 min total including warm-up. 5 min. warm-up of “light” jogging. Followed by 5 intervals of 2 minutes each. 95% of max HR Over 12 week period, 480 minutes of training were completed

Procedure Training: prolonged moderate “traditional” running group (MOD) Average number of completed sessions a week was 2.5 Total training time of approximately 1800 minutes over the 12 week period 1 hr of continuous running at 80% max HR Approximately 65% of VO2 max

Procedure Training: Strength training group (STR) 2 sessions per week. Total exercise time was 60 min. per session. Total exercise time over the 12 week period was 1500 min. 3-4 sets of squat, hack squat, incline leg press, isolated knee extension, hamstring curls, and calf-raises. 1 min. rest between sets. HR averaged 50% of max HR. Loads corresponded to reps during the first 4 weeks. Changed to 6-10 reps during the last 8 weeks. Weight load was gradually adjusted to match progression.

Results: INT group High intensity interval running (INT) is an effective training stimulus for improvement of cardiorespiratory fitness and glucose tolerance. Also increases VO2 max. May induce significant reduction in systolic blood pressure in untrained subjects. Intense interval running (INT) had no impact on muscle mass or indices of skeletal health. Less effective for treatment of hyperlipidemia and obesity than prolonged training.

Results: MOD group VO2 max improvement was only half that of INT. Reduced diastolic blood pressure more than INT. Cholesterol decreased significantly. Increases glucose tolerance comparable to INT. Significant reduction in subject weight and body fat %. Improved lipoprotein-lipid profile. No significant effect on muscle or bone mass.

Results: STR group No significant effect on aerobic fitness. No noticeable effect on VO2 max. No significant effect on blood glucose tolerance. Large increase in total body weight and lean body mass. Slight decrease in systolic blood pressure. Significant increase in muscle and bone mass. Increased bone mineral content. Induced osteogenic stimulus that may have both accute and prolonged effects for musculoskeletal health. Fasting insulin levels were not changed in any of the 3 groups.

Variables Independent Exercise training High intensity interval running (INT), moderate intensity “traditional” running (MOD), and strength training (STR). Dependent General health VO2 max, body fat %, blood pressure, glucose tolerance, lean body mass, bone mass, and metabolic fitness. Relationship being examined The effects of different types of training on multiple aspects of physical health.

Hypotheses No explicit hypothesis. The researchers were conducting the experiment to find a baseline of results.

External Validity Attempting to generalize to all people. Sample was all men. If the study included women results for body fat % and lean muscle mass and bone mass could differ due to physiological differences. The participants were untrained and had not participated in any regular physical training for at least 2 years. Strengthens external validity because it helps the study generalize to the entire population and not just regularly physically active people. Overall, the external validity was strong.

Construct Validity Independent variable Exercise training High intensity interval running (INT), moderate intensity “traditional” running (MOD), and strength training (STR). Mono-operation bias Does not apply because of the different of intensities of exercise training and the differing amount of time spent in training throughout the 12 week period. Confounding constructs and levels The training time in the INT group was less than 1/3 of the time completed by the two other groups. However, the results still showed that the INT group was most effective for cardiorespiratory fitness and glucose tolerance so this wasn’t much of a threat Unintended consequences 3 subjects in the INT group missed between 1-4 training sessions due to overuse injury (shine splints, etc.) This should not have effected results.

Construct Validity Dependent variable General health VO2 max, body fat %, blood pressure, glucose tolerance, lean body mass, bone mass, and metabolic fitness. Mono-method bias Not a factor in this study because of the different aspects of general health that were measured. VO2 max, max HR, body %, etc. Overall, we found the construct validity to strong.

Internal Validity The study does not specify whether the assignment was random or not, so we can’t specify where the threats lie in multiple group and social threats. Study design O X1 O O X2 O O X3 O O O

Internal Validity Control group learning about treatment and imitating the experimental group on their own is a possibility. However, the results don’t show this to be a factor. Resentful demoralization could have taken place as well but we don’t know if the subjects were randomly assigned.