Acute Cardiorespiratory and Metabolic Effects of a Sandbag Resistance Exercise Protocol
The purpose of the present study was to examine the acute cardiorespiratory and metabolic effects of a sandbag (SB) resistance exercise protocol and compare the responses to time-matched treadmill running protocols. Eight healthy, resistance-trained men (21.1 ± 1.0 years; 86.1 ± 7.8 kg) completed four protocols of equal duration in random sequence: 1) SB, 2) treadmill running at 60% of VO2 reserve (60VO2R), 3) treadmill running at 80% of VO2 reserve (80VO2R), and 4) a control protocol. The SB protocol was 16 min in duration and consisted of 3 circuits of 8 multiple-joint exercises (with 11-, 20-, or -48 kg sandbags) performed for as many repetitions as possible for 20 sec followed by a 10-sec rest interval prior to beginning the next exercise. Two minutes of rest was allowed between circuits. Breath-by-breath oxygen consumption (VO2) and heart rate (HR) were recorded throughout each protocol and for 30 min post exercise (PE) and blood lactate was determined prior to and immediately following each protocol. Blood lactate was significantly higher following SB compared to 60VO2R and 80VO2R. Mean and peak HR in SB was significantly higher than 60VO2R but not different from 80VO2R. Mean VO2 and energy expenditure (EE) in SB was significantly lower than 60VO2R and 80VO2R during each protocol but significantly higher following SB compared to 60VO2R and 80VO2R PE. Compared to 60VO2R and 80VO2R, respiratory exchange ratio was significantly higher during SB and through 5 min PE, but was significantly lower at 25 to 30 min PE following SB. SB as performed in the present study provides a superior metabolic stimulus to treadmill running during the PE period; however, the SB results demonstrate inferior EE compared to running at 60VO2R and 80VO2R.