ABSTRACT
This study aimed to examine a new walking method to fulfill the Physical Activity Reference for Health Promotion in Japan in a shorter time, which can be performed as a non-exercise activity (NEA) such as walking during commuting. Eleven healthy subjects performed normal walking (NW) and knee-up walking (KU) for eight minutes without load (0%) and with loads of 5, 10, and 20% of body mass in a backpack carried on the back (NW-0, 5, 10, and 20; KU-0, 5, 10, and 20) on a treadmill at a speed of 5 km/h at 0% tilt. Oxygen uptake, blood lactate levels, and ratings of perceived exertion (RPE) were measured in the last two minutes of each walking stage. Metabolic equivalents (METs) were also calculated from the resultant oxygen uptake. METs in NW-20 and all weight conditions of KUs were significantly greater (P < 0.01) than those in NW-0 (3.8 ± 0.1 METs). RPE in both KU-10 and KU-20 was above 15 (i.e., indicating Hard). Blood lactate levels in the KU-20 (4.5 ± 0.7 mmol/L) were above the Onset of Blood Lactate Accumulation. On the other hand, NW-20, KU-0, and KU-5 were physical activity level of moderate- to vigorous- intensity that could be performed as a NEA. These data suggest that our new walking methods such as NW-20, KU-0, and KU-5 can satisfy the Physical Activity Reference in a shorter time rather than normal walking, and could be continuously performed in daily life.