Running At ‘Pace with A Smile’ Exceeds Intensity of Lactate Threshold in Elderly People

Abstract

Open Access Research Article fitness level [6, 7, 8]. Regarding jogging, commercially available heart rate monitor is convenient to set an individual exercise intensity, but Borg's rating of perceived exertion (RPE) scale is thought to be realistic and simple method to set an optimal exercise intensity for elderly people [9]. RPE at LT in running has been reported in numerous studies. These RPE responses are within the range of RPEs reported in previous studies, such as 10.8±1.8 , 11.2±2.1 , 11.2±2.3 , 11.2±2.1 [12], 11.6±0.7 and 11.0±1.1 [10-14]. In light of these data, it is expected that one can run at LT intensity if prescribed based on 10-12 of RPE scale. We conducted a randomized control trial for community-dwelling elderly people aged 70.4±4.1 , demonstrating that Metabolic Equivalents (METs) at LT was 3.8±0.5 before intervention, which was calculated 2.9 km/h of running speed [6,15]. Given that the speed human preferably transition from walking to running (Preferred Transition Speed or PTS) is 5.9-7.9 km/h, LT in elderly people is within the range of walking speed. There is no significant difference in PTS between runners and non-runners, suggesting that PTS is not affected by aerobic capacity [16-19]. If the elderly people run around PTS, they can easily exceed the LT intensity. So far, we have called a pace at RPE 10-12 or LT intensity 'Pace with a Smile' to make this phrase generally known. The purpose of this study was to test the hypothesis that running at pace with a smile (RPS) can exceed LT intensity. Therefore, three tests were randomized as follows; 1) outdoor test of 1 min RPS, 2) treadmill test of running to determine LT intensity and 3) test of PTS. It is still unclear whether RPS exceeds LT intensity or not, or become high intensity exercise in elderly people. It is clarified that when running based on RPE obtained from the graded exercise test, it becomes faster than the speed on the treadmill [20,21]. However, our research design is that runs directly based on 'pace with a smile' to confirm whether it exceeds LT intensity. Most people tend to have an impression that running is a hard exercise. But, if this hypothesis is verified and it is found that even if running at pace with a smile exceeds the threshold at which aerobic capacity increases, it will be useful information for those thinking that running should run fast. Abstract Aim: Moderate exercise intensity at the lactate threshold (LT) is considered to be the minimal intensity required to increase aerobic capacity. Purpose: The purpose of this study was 1) to examine the benefit of running at a pace at which the runner can run with a smile ('pace with smile' / RPS) to compare LT in running and 2) to examine how much the LT speed in running differed from preferred transition speed (PTS) in 17 elderly people (Age: 71.0±5.2 yr, Height: 154.4±7.6 cm, Body mass: 56.7±8.0 kg, BMI: 23.8±2.7 kg/m 2). Methods: An outdoor test of 1 min RPS was carried out based on 10-12 of Borg's RPE scale (around 'fairly light') or at perceived smiling and talking level, and distance was measured in order to calculate running speed. LT in running was determined by incremental exercise test. PTS was determined as a natural walk-run transition speed by increasing treadmill speed from low to high, and reducing it from high to low for run-walk transition. These tests were randomized. Results: Even if prescribing running at smiling and talking level, the speed of RPS exceeded the LT speed in running (6.6±0.5 vs. 4.8±0.8 km/h, P<0.01). LT speed in running was significantly lower than PTS (4.8±0.8 vs. 5.9±0.7 km/h, P<0.001). Conclusion: These data indicated that 1) Running at smiling pace easily exceeds the aerobic training threshold and 2) LT speed in running is slower than PTS, indicating that slow-jogging at walking speed is optimal in elderly people.