本論文は，日常生活における歩行時の運動強度推定精度を高めるために，歩行速度，
歩行率，歩幅を様々に変えた条件での酸素摂取量の測定を行い，その結果から歩行運動 における運動強度推定式を作成した．
第2章では，運動強度の推定を行う前段階として，歩行率・歩幅統制条件における歩 容変化についての確認と，歩幅統制条件における先行動作による歩容への影響について の検討を行い，その結果をまとめた．
歩行率統制条件においては歩幅，Walk Ratioに個人差があり，一定の歩行様式とはな らないことが示唆された．一方，歩幅統制条件においては，Walk Ratioは歩幅の大きさ に伴い変化することから，歩幅を変化させた時の歩行速度変化に対する歩行率の貢献度 は低く，主に歩幅の要因によって歩行速度が変化することが分かった．以上のことから，
歩行実験の際には指示の与え方によって，歩行様式がそれぞれ異なることが示唆された．
歩幅統制条件時の先行動作による影響に関しては，先行動作の影響による歩幅変化が 起こる可能性は低いと考えられる結果が得られた．先行動作の影響を確実に排除するた めには，試技間に十分な休憩を挟むこと，試技の順序をランダムに設定することなどの 対策が必要であると考えられた．
第3章では，前章の結果をもとに歩行条件のプロトコルを決定し，歩行速度と歩行率，
歩幅の様々な歩行条件における酸素摂取量の計測を行い，運動強度の値を算出した．そ の値から，歩行速度，歩行率，歩幅が運動強度にどのような影響を与えるのかを確認し，
歩容変化に伴う運動強度推定式を算出した．
自由歩行時については，歩行速度がMETsに与える影響が大きく，歩行速度を説明変 数として用いた時に精度の高い式が得られた．しかし，歩行速度を一定とし歩行率・歩 幅を意図的に変化させた歩行では同じ歩行速度でも運動強度の値が変動したため，歩行 速度のみでは回帰式の精度が落ちることが明らかとなった．そのため，METsの値に影 響を及ぼしたと考えられる歩行率や歩幅を説明変数に加えたところ，より精度の高い回 帰式を作成することができた．日常生活における歩行を想定した上で最適な運動強度推 定式は，本研究の検討から以下の式によって表すことができると考えられる．
METs = 1.16 × 10−4SR2− 7.33SL + 9.41SL2+ 2.66 (R2 = 0.70)
（SR：歩行率，SL：歩幅）
ただし，この推定式の妥当性および精度については明らかとすることができなかったた
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め，今後，さらなる検討が必要である．しかしながら，自由歩行も含めて説明変数とし て歩行速度だけではなく歩行率や歩幅を加えることで，より精度を高く運動強度の推定 を行えることが示唆された．
本論文で提案した歩行運動における運動強度推定式の妥当性，精度の保証がされれば，
歩行速度，歩幅，歩行率を測定・推定可能な活動量計などに組み込まれることで，歩行 率・歩幅変化に伴う運動強度がNCDリスクに及ぼす影響を疫学的な視点から調べるこ とが可能となり，これまで明らかとされていない歩行時の歩行率や歩幅の重要性につい て検証することができるようになると考えられる．また，歩行率と歩幅を考慮した推定 式が既存の運動強度推定式よりも高精度なものとなれば，日常生活の運動強度と NCD の関連性について新たな知見が得られるかもしれない．さらに，近年は計測した情報を リアルタイムに計測対象者が確認できるようなサービスが展開されており，様々な歩容 における歩行運動時の運動強度をリアルタイムで確認するようなサービスの提供にも 発展するなど，様々な応用にもつながる可能性が考えられる．
本研究が，このような歩行運動の新たな知見を生み出し発展する先駆けとなることを 願う．
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