Koji Sugiyama

Oxygen uptake, heart rate, perceived exertion, and integrated electromyogram of the lower and upper extremities during level and Nordic walking on a treadmill

The purpose of this study was to characterize responses in oxygen uptake (V·O2), heart rate (HR), perceived exertion (OMNI scale) and integrated electromyogram (iEMG) readings during incremental Nordic walking (NW) and level walking (LW) on a treadmill. Ten healthy adults (four men, six women), who regularly engaged in physical activity in their daily lives, were enrolled in the study. All subjects were familiar with NW. Each subject began walking at 60 m/min for 3 minutes, with incremental increases of 10 m/min every 2 minutes up to 120 m/minV·O2 ,V·E and HR were measured every 30 seconds, and the OMNI scale was used during the final 15 seconds of each exercise. EMG readings were recorded from the triceps brachii, vastus lateralis, biceps femoris, gastrocnemius, and tibialis anterior muscles.V·O2 was significantly higher during NW than during LW, with the exception of the speed of 70 m/min (P < 0.01).V·E and HR were higher during NW than LW at all walking speeds (P < 0.05 to 0.001). OMNI scale of the upper extremities was significantly higher during NW than during LW at all speeds (P < 0.05). Furthermore, the iEMG reading for the VL was lower during NW than during LW at all walking speeds, while the iEMG reading for the BF and GA muscles were significantly lower during NW than LW at some speeds. These data suggest that the use of poles in NW attenuates muscle activity in the lower extremities during the stance and push-off phases, and decreases that of the lower extremities and increase energy expenditure of the upper body and respiratory system at certain walking speeds.

Relationship between perceived exertion and blood lactate concentrations during incremental running test in young females.

BackgroundTo investigate more practical handling of Borg’s ratings of perceived exertion (RPE) and category-ratio scale of RPE (CR-10), we evaluated interrelationships between RPE, CR-10, and blood lactate concentrations (bLa) during incremental treadmill running tests for young females with different aerobic fitness levels.MethodsOxygen consumption, heart rate, bLa, RPE, and CR-10 were measured from distance runners (DR; n = 15), race walkers (RW; n = 6), and untrained females (UT; n = 11). These variables corresponding to the lactate threshold (LT) and onset of blood lactate accumulation (OBLA) were compared among these groups.ResultsThe UT had significantly lower RPE at LT than DR and RW, although the CR-10 at LT was not significantly different among these groups. The CR-10 at OBLA was significantly lower for the UT than DR. The relationship between bLa and CR-10 was approximated well by two linear regression lines in all groups. The bLa at the intersection only for the RW was significantly lower than that at LT, however, such intersections were observed at CR-10 = 3.1 to 3.2 without significant group differences. The CR-10 scores at LT and intersections were not significantly different in each group.ConclusionThese results suggested that an intersection between CR-10 and bLa was observed at the CR-10 score around three points of first half regardless of the aerobic fitness levels in young females, and such CR-10 scores would be associated with LT.

A Comparison of the Degree of Perceived Exertion by Participants In Nordic Walking and Level Walking at Equal Levels of Relative Exercise Intensity

It has been reported that the perceived exertion in level walking (LW) is the same with or lower than that of nordic walking (NW), although the exercise intensity of NW is higher than LW. Based on this fact, it could be expected that absolute intensity, the speed, should differ if the relative intensity, measured using VO 2 level, is the same in both types of walking. This study aimed to clarify the levels of perceived exertion between NW and LW when their VO 2 levels are equivalent. The subjects were eight healthy young males who exercise regularly. They performed three tests: an incremental test to obtain their regression formula between theVO 2max and the speed, the submaximal exercise test of NW (the NW condition) at 40% of each subjects VO 2max speed, and LW test (the LW condition) at the speed we substituted the value of VO 2 provided in the NW condition into the regression formula. They conducted a six-minute exercise in each condition. Measurements included percentage of VO 2 , heart rate reserve (%HRR), and perceived exertion (OMNI scale) of their upper limbs, lower limbs, and whole body. Although there was no significant difference in VO 2 and %HRR, there was in speed, with the subjects walking faster in the LW condition (p<0.01). No significant difference was found between the conditions on the OMNI scale of their whole body and lower limbs, but the NW condition produced significantly higher values than the LW condition for their up- per limbs (p<0.01). The results suggested that the same exercise intensity can be obtained at a slower speed in NW, and higher exertion was perceived only in their arms in NW, with no difference in their lower limbs or whole body.

Effect of rising body temperature on respiratory chemosensitivity to CO2.

A rise in body temperature (Tb) is known to cause minute ventilation (VE) to increase. However, the mechanism of the ventilatory response to rising Tb is still unclear. In the context of the relationship between VE and Tb, it is known that respiratory chemosensitivity is influenced by Tb, and that a rise in Tb of more than 0.7 °C enhances respiratory chemosensitivity [1]. It is not known, however, whether increases in Tb less than 0.7 °C also influence respiratory chemosensitivity. The aim of this study was to clarify the effect of mild hyperthermia (0.3 °C and 0.7 °C) on respiratory chemosensitivity.