Objective: The purpose of this study was to investigate effects two kinds of isotonic muscle contraction training on muscle body shape and neck-shoulder muscle activity among college students with physical inactivity and poor body posture, to provide appropriate exercise options for these college students. Methods: Thirty subjects with typical sedentary behavior and upper-cross syndrome were randomly divided into no load isotonic training(IT),resistance isotonic training(RIT) and health education control(C) groups. Two training groups were trained for 12 weeks. All subjects were tested their heath-carter anthropometric somatotype,cervical spine angle,range of cervical spine extending and scapula adduction,surface electromyography data of neck and shoulder musle activity were measured before/after training. Results: After training,three factors value in IT, RIT, C groups were[(3.68±1.01)(5.68±1.05)(3.17±0.54)，(2.84±0.84)(5.87±1.45)(1.34±0.10)，(3.82±0.18)(4.83±1.03)(3.30±0.22)] respectively. After training,cervical spine angles were(32.70±9.20)(20.78±2.24)(11.24±3.21)°; extending angles of cervical spine were(3.21±1.82)(2.24±0.60)(1.24±0.01)°; ranges of scapula adduction were(3.44±1.28)(3.08±1.35)(6.08±1.57)cm in IT, RIT, C groups respectively. Three parameters in two training groups significantly increased(F=8.43, 7.29, 8.04, P<0.05). Antagonistic muscle coactivation in neck and shoulder in three groups were(0.11±0.01) and(0.34±0.02)(0.31±0.01) and(0.56±0.03)(0.36±0.11) and(0.69±0.04) respectively,which significantly decreased in two training groups(F=27.39,5.45,P<0.05). There were more obviously changes of neck and shoulder musclebone system in IT group(P<0.05). Conclusion Musculoskeletal system improved while body fat reduced after resistance isotonic training. No load isotonic training was more superior in adjusting and correctingg upper-crossed syndrome posture than resistance isotonic training. College students with sedentary behavior and upper-cross syndrome can choose no load isotonic training preliminarily for muscle strength and concordance increasing before adding load.