Presentation on theme: "Grant Weaver, Sam Vaninger, Brett Vihnanek. This study was meant to examine the acute effects of a caffeine- containing supplement on upper and lower."— Presentation transcript:
This study was meant to examine the acute effects of a caffeine- containing supplement on upper and lower body strength and muscular endurance as well as anaerobic capabilities. 37 resistance trained men volunteered to participate in this study. Participants then went through 2 Wingate tests to determine peak power, and did a 1 rep max test on bilateral leg extension and free-weight bench press exercises. They rested for at least 2 days before coming back to take the tests again in which participants were randomly assigned to 1 of 2 groups. Group 1 was given a caffeine-containing supplement while group 2 was just given a placebo. 1 hour after ingestion participants went through the same tests again and found an increase in bench press in the caffeine-containing supplement group, while all other forms of strength were the same. Thus, the caffeine- containing supplement may be an effective supplement for increasing upper body strength and, therefore, could be useful for competitive and recreational athletes who perform resistance training.
The caffeine containing supplement (IV) will increase upper and lower body strength (DV)as well as muscular endurance (DV) and anaerobic capabilities (DV)
37 resistance trained men between the ages of 19 and 23 All had at least one year of resistance training for 3-4 days per week. The subjects varied in both height and weight No history of medical or surgical events that could affect the study None were on any medications No use of nutritional supplements (protein, creatine, etc) 6 weeks before the study Hadn’t participated in any other studies within a month of being screened for this trial.
Participants were volunteers Random assignment Double blind Placebo controlled Parallel design
For the first visit, the subjects performed 2 Wingate tests to determine peak power and mean power. Wingate test is the most popular anaerobic cycling test Previous studies reported that it is both a reliable and valid method to measure anaerobic capabilities. Subjects cycle against low resistance for 4 min. to warm up. At command, the subjects then pedaled for 30 seconds as fast as possible against a resistance equal to 7.5% of their body weight. After a break, the subjects repeated this. Peak power = highest output (rpm) in a 5 second period Mean power= Average output over 30 seconds Average PP and MP from the two tests were the used for statistical analysis.
24 hours after the Wingates, the subjects returned to test muscular strength and endurance 1 rep max out for barbell bench press and bilateral leg extension to test strength To determine max out, heavier loads were added until subject couldn’t complete lift. This was usually achieved within about 5 trials 2 minutes rest was given between all trials. After 1 RM was determined, subjects rested for 2 min and performed as many reps as possible at 80% of their 1 RM on LE and BP to determine total volume lifted (muscular endurance).
48 hours later, the subjects returned and were given the treatment. Randomly assigned into a supplement and placebo group (17 in SUPP, 20 in PLAC) Supplement contained approx. 200 mg of caffeine Placebo was microcrystalline cellulose The Wingates, 1 RM, and total volume tests were then repeated in the exact fashion as they were in the pretest one hour after the supplement was ingested.
When compared to the placebo, the supplement had no effect on LE 1RM, LE TOTV, BP TOTV, PP, or MP However, the supplement resulted in a mean 2.1 kg increase in the 1RM for BP This concludes that caffeine may be an effective supplement to increase upper body strength and could be useful for competitive and recreational athletes performing resistance training.
Interaction of selection and treatment: The study only looked at resistance trained men aging from roughly 19-23. The study could have produced different results between different age groups, gender, and amounts of resistance training. Simply testing one demographic doesn’t allow for generalization.
Interaction of setting and treatment: The subjects were only tested in a lab. Results may have varied depending on if they were tested in a competitive or recreational environment. However, this doesn’t really seem to be much of a threat to validity, as being in a different place doesn’t change any of the movements or lifts.
Interaction of history and treatment: The caffeine was ingested 1 hour before the post test. The results may have varied had they been given the treatment closer to their test or even over an hour before it.
There were two separate groups, which eliminated single group threats. The groups were randomly assigned, eliminating any multiple group threats. The study was double blind, so neither the subjects nor experimenters knew who was ingesting the SUPP and who was ingesting the PLAC. This eliminates all social interaction threats. R 0 X1 0 R 0 X2 0 Overall, the internal validity for this study seemed very good.
Inadequate preoperational explication: All tests have been used many times in the past to measure what they were supposed to measure and all had been found to be valid tests, eliminating this threat. Mono-operation bias: Each aspect of the study could have been measured in more than one way. For example, upper body strength could have been measured in more ways then just barbell bench press. Incline BP, dumbell bench press, machine bench press are all other ways to measure upper body strength, but only one was used.
Mono-method bias: Change in strength could be measured in different ways. For example, bench press mainly uses chest, triceps, and shoulder muscles, but bicep curls use different muscles, and they are obviously part of the upper body. However, bench press uses the most upper body muscles out of any upper body lift, making it seem like the best demonstration of strength.
Interaction of Different Treatments: There aren’t outside factors that would have had any effect on the results in the time this experiment was conducted. Interaction of testing and treatment: All the subjects were already experienced in resistance training, so one additional trial would not likely implicitly improve performance.
Confounding constructs and levels: This is probably the biggest threat to the entire experiment. All subjects varied in size, but all were given the same dose of caffeine. There could be differences in results if more trials were given with varying amounts of caffeine. Or, caffeine could have been dosed proportionately to body weight.