**6. Rehabilitation training in water for regaining normal walking, is it truly effective?**

The EMG characteristics introduced in this chapter are used in the comparison of the EMG data such as mean value or quantity. However, it is important to evaluate the quality of EMG signal to identify where the stimulus happened as the mean value is nothing more than the representative mean of the data for the targeted period. The quality analysis for EMG signal of exercise in water is a comparison of the wave forms that accompany exercise movement. Normalization from 0 to 100% of one cycle was applied so as to compare the muscle activity time course pattern [26, 34]. However, there was no statistical comparison made to the time course pattern. Instead the authors compared the time course pattern of walking exercise in water and on land by applying a cross correlation function. This correlation was then used in discussing the similarity of muscle activity patterns between water- and land-walking, as well as the usability of walking in water as a form of rehabilitation training. The hypothesis being that a water environment may have the benefit of less gravity stress and greater safety in preventing falling accidents. In addition, training of the targeted movement may be more effective and movement function specific [35] in water than on land. Thus, further investigation of the similarity of muscle activity between water- and land-walking would provide increased understanding regarding the use of water activity and exercise prescription for rehabilitation.

Values are mean ± SD of the subjects A: TA, B: GAS, C: RF, D: BF LW: land-walking, WW: water-walking r: cross correlation coefficient

As seen in the figure 21, normal running in water stimulated every muscle except the RA and the OEA muscles compared to the other exercise forms. This indicates normal running provides a high intensity activity for these muscles. The DWR was apparently an effective exercise for the BF, AL, RA and OEA muscles, especially abdominal muscles as seen in the comparison with water- and land-walking in the former section. The walking with kicking exercise clearly activated the VL and RF because those muscles were the agonist muscle for the walking with kicking motion, and this exercise stimulated abdominal muscles slightly more when compared to the other exercises. The VL muscle activity was comparably higher in the normal running, side walking, walking with long step, walking with trunk twisting and walking with kicking than the other exercises which may be due to those exercises requiring the body to be immersed deeply or require stronger extension of the knee joint during this motion. The walking with knee up exercise could be said to be of a low intensity exercise as it showed lesser EMG values than the others in every muscle. The walking with elbow-knee alternative touching exercise tended to show a high muscle activity especially in the hip and trunk muscles. It was speculated that the muscle activity for this exercise happened during standing phase in measured muscles resulting from the attempt to stabilize against upper body motion moving dynamically. As just described, the figure showed the features of the muscle activity modality during several exercises in water, but further video analysis investigation

would be needed for understanding the cause of the muscle activity more precisely.

F: forward walking, B: backward walking, D: DWR, R: normal running, S: side walking, L: walking with long-step, T: walking with trunk-twisting, K: walking with kicking, U: walking with knee-up, P: walking with elbow-knee alternative

**Figure 21.** The mean %MVC value of the lower limb, hip and trunk muscle during exercise in water. [Unpublished

(A) (B)

230 Electrodiagnosis in New Frontiers of Clinical Research

(C) (D)

A: shank muscles, B: thigh muscles, C: hip muscles, D: trunk muscles

touching

data]

**Figure 22.** The normalized time course pattern of %MVC during walking in water and on land. [Modified from refer‐ ence [36]

In the study by the authors [36], nine male subjects walked in water and on land condition at self-selected slow, comfortable, and fast speed in water as well as comfortable speed on land. During each effort, the muscle activity of TA, GAS, RF and BF were collected at 2000Hz with a time constant of 0.03sec equal to 5.3Hz high-pass filter. After the collection, the data was filtered with low and high pass filter of 500Hz and 10Hz, respectively. Then, the data was fullwave rectified and low-pass filtered with moving average at 5 Hz to obtain the linear envelope. Following this, the data was normalized from heel contact (0%) to next heel contact (100%), and expressed as %MVC. The comparison was then made between each water-walking speed and confortable speed of the land-walking.

results the authors concluded that muscle activity would probably decrease in DWR, when compared to land treadmill running. In addition, the muscle activity modality can be changed significantly byusingdifferentflotationdevices.Inthe results ofthe comparisonbetween water exercise and land exercise, the muscle activity modality was affected by the physical qualities of water (buoyancy and water resistance). For example, horizontal movement in water tended to increase agonist muscle activity, hence vertical movement and horizontal- and verticalincluded-movement decreased agonist muscle activity. The water physical qualities would affectthe posture during exercise and resultin changes to muscle activity modality. The muscle activity characteristics in fundamental variations of water-walking vary its pattern resulting in unique movements, and the characteristics basically conform with exercise direction. Run‐ ninginwater,withfeettouchingthebottomoftheswimmingpool,generatedthehighestmuscle activity. Walking in water with knee up has the lowest intensity among variations of water

Underwater Electromyogram for Human Health Exercise

http://dx.doi.org/10.5772/55115

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This chapter introduced research comparing the EMG of water-walking to land-walking. The results concluded that the shank and thigh muscle activity during water-walking was similar to that of land-walking. Identifying the water environment can simulate land-walking in respect to muscle activity even at slow speed. This reinforces the concept in water environment as a legitimate and effective exercise. In addition, the water environment provides increased safety with respect to falls. In summary, the water environment would be very beneficial especially not only for the physically fit but also for people wishing to regain the normal motion

The authors thank PhD Hitoshi Wakabayashi in Chiba Institute of Technology, PhD Daisuke Sato in Niigata University of Health and Welfare, and Professor Takeo Nomura in NPO Tsukuba Aqua Life Research Institute for your contributing to the data collection related in

and Brendan Burkett4

, Mark Mckean4

\*Address all correspondence to: kkaneda@sea.it-chiba.ac.jp

2 Education Center of Chiba Institute of Technology, Japan

\*Address all correspondence to: koichi@sfc.keio.ac.jp koichikaneda.japan@gmail.com

1 Graduate School of Media and Governance, Keio University, Fujisawa City, Kanagawa, Ja‐

exercise when exercising in self-selected moderate pace.

which may be difficult to achieve on normal land environment.

**Acknowledgements**

this chapter.

pan

**Author details**

Koichi Kaneda1,2,3\*, Yuji Ohgi1

A normalized time course pattern and results of the cross correlation analysis are shown in Figure 22. The cross correlation coefficients were moderate in the RF and BF (r = 0.53 - 0.70), and were high in the TA and GAS (r = 0.83 - 0.90). This showed the muscle activity pattern of the water-walking were similar to that of the land-walking even in the slow and fast speed. Moreover, as seen in the figure 22, the muscle activation was higher during the water-walking than land-walking during most part of one full stride for all muscles except the GAS. This suggests the water-walking would be able to simulate the land-walking very closely regardless of the speed of the water-walking, and stimulate the thigh muscles and TA sufficiently even in the slow speed. The authors also suggest that even during slow speed, water-waking is an effective exercise modality for muscle training in a similar way to normal walking on land.

A possible limitation can be seen when applying normalization method to time course pattern in that the normalization process resulted in apparent cancelations in time length changes which may alter the sequencing and timing of events especially in exercise in water due to the buoyancy and water resistance affect on the movement duration. In addition, changing the time length may also distort the time course pattern, where the exact timing may not be comparable between the same timing of two wave forms (i.e. does the 50% of land-walking truly match to the 50% of water-walking in normalized data?). This should be considered in studying outputs from EMG modality of water-walking.
