The purpose of the present study was to investigate a useful exercise protocol and method of evaluation for determining the gas exchange threshold (VO₂GET) and correlation coefficient between VO₂GET and maximal oxygen uptake (VO₂max), which is an index of aerobic capacity. Five healthy male volunteers (age: 25.6 ± 2.0 yrs; height: 172.9±4.0 cm; weight: 69.5±6.6 kg) performed exercise tests 82 times. Each volunteer randomly conducted a RAMP exercise (1 W⋅3 sec^-1), STEP-1 exercise (20W⋅min^-1) and STEP-2 exercise (40W⋅2 min^-1), respectively, at least 4 to 8 rotations. The gas exchange parameters (VE, VO₂and VCO₂) for incremental exhaustive cycle ergometer exercise were measured using a“breath-by-breath”method. Three different methods of evaluation- (VE/VO₂and VE/VCO₂) exchange (M-1), V-slope method (M-2), and M-1 & M-2 (M-3) -were attempted to determine VO₂GET. The VO₂GET values, determined by three different methods (M-1, -2 and -3) of evaluation, were classified as‘easy’ (J-A) and‘difficult’ (J-B) in all tests. Reproducibility of VO₂max and VO₂GET were assessed using the coefficient of variation (CV) and correlation coefficients (r) between VO₂max and VO₂GET.
The results are summarized as follows:
1) The means of the reproducibility of VO₂max were determined among the 5 subjects by us ing RAMP, 4.8% (n=25), STEP-1, 3.1% (n=28) and STEP-2, 2.9% (n=29) exercise tests; STEP-2 exercise test values (CV) were lower than the others. There was no significant difference in the means of VO₂max among the 5 subjects according to the RAMP and two STEP exercise tests (Two-way ANOVA) .
2) The best reproducibility value of VO₂GET among the 5 subjects was determined using RAMP exercise tests with the V-slope method (M-2) and evaluations were classified as easy (J-A) . The value (CV) was 2.8%. There was no significant difference in the VO₂GET values (M-1 (J-A, -B), M-2 (J-A, -B) and M-3) (Two-way ANOVA) and their means among the 5 subjects concerning RAMP and two STEP exercise tests (Two-way ANOVA) .
3) The best correlation coefficient (r) value between VO₂max and VO₂GET was obtained using RAMP exercise tests with M-2 (J-A) (r=0.976, n=20) .
The present results indicate that the most useful exercise protocol and method of evaluation for determining VO₂GET is the RAMP exercise test with the V-slope method.

The ability to walk is just as important for the elderly as it is for young people. In fact, in the elderly, decreased mobility limits function in daily life and can lead to more serious situations (e.g., becoming bedridden) . The elderly population has increased over the last decade, and many researchers have studied the mobility of the elderly. However, the focus of most studies has been to facilitate recovery of bedridden individuals and prevent the elderly from becoming bedridden, and particularly to prevent fall-induced fractures, which often cause the elderly to become bedridden. However, about 70-80% of the elderly population do not require care, and it is necessary to conduct research on the maintenance of activities of daily living to make it possible for the elderly to work or volunteer. From this perspective, mobility is an important physical factor. Mobility is dependent on muscle activity and it has long been known that aging reduces muscle mass. Therefore, it is feasible to assume that reduced muscle mass leads to decreased ability to walk, and we have proven that there is a close correlation between the two. When presenting the idea of strength training to the elderly, it is appropriate to focus on the maintenance and improvement of mobility, not on the training itself. The results of our research can be summarized as follows:
Muscle mass decreases with age, with the legs being affected to a greater degree than the arms. Moreover, muscle atrophy is dependent on weakening of muscle fibers, especially fast-twitch (Type II) fibers. Reduced lower limb muscle mass increases the risk of falling and can decrease walking ability to a degree that can affect daily living activities.
In order to improve reduced muscle mass in aging, it is important to use an exercise program that is designed to strengthen fast-twitch fibers, which can be followed even by the elderly. Since walking therapy mostly mobilizes slow twitch fibers, it is not effective in preventing and improving muscle atrophy. It is important to have an exercise program that is designed to mobilize fast-twitch fibers.