Background: Evaluation of power-force-velocity profiles in ballistic push-offs and in sprint movements are beneficial to enhance sport performance. There have only been a few studies investigating force-velocity profiles in rotational movements and there have not been any studies conducted on golf specific rotational movements. There is a lack of isoinertial power assessment protocols which can relate to golf swing performance. For this reason, 1080 Quantum was used for testing which is a machine able to measure power, force and velocity in several different resistance modes. Aim: The aim was to study the reliability of three golf specific rotational tests and to assess the reliable test’s validity. The secondary aim was to study the isoinertial force-velocity and power relationship in tests that assessed acceptable test-retest reliability and acceptable construct validity. Methods: Twelve high level golfers (handicap -1.5±1.2), 8 men and 4 women performed the tests with five different loads; 2 kg, 6 kg, 10 kg, 14 kg and 18kg with three golf specific rotational movements in a motorized cable machine (1080 Quantum, Sweden). The three new tests utilized were: full body rotational test (FBRT), thorax rotational test (TRT) and pelvis rotational test (PRT). Data gathered was used to study golfer’s individual force-velocity profile and to assess construct validity of the reliable tests against previously recorded normal-swing driver clubhead speed (CHSnormal), and maximum-swing driver clubhead speed (CHSmax). Construct validity was based on á priori stated hypothesizes, and data were analyzed with Spearman’s correlation coefficient (rs). Intraclass correlation coefficient (ICC) and coefficient of variation (CV) was used to assess test-retest reliability of FBRT, TRT and PRT. Results: In the reliability assessment, the highest peak power (PP) (ICC, 0.968, 95% CI (0.889- 0.991)), corresponding peak force (PF) (ICC, 0.993, 95% CI (0.96- 0.998)) and corresponding peak velocity (PV) (ICC 0.773, 95% CI (0.17- 0.936)) was only found to be acceptable in FBRT. Construct validity assessment of FBRT was not found acceptable in either of the resistances. The calculated average slopes indicated a velocity dominant force-velocity profile for women and a force dominant for men. Conclusion: The study demonstrated that only the FBRT assessed acceptable test-retest reliability for measuring force, velocity and power. Based on our hypothesizes FBRT is not a valid indicator of golf performance on either resistance, however it had a significant moderate to good correlation with CHSmax and with CHSnormal at all resistances apart from 2 kg. FBRT should not be applied as a test, nor to be used for the calculation of the force- velocity profile since it is not valid, even though it is reliable. since it is not valid, even though it is reliable. As a result, FBRT could only be used for exercise and needs further development to improve its validity. / <p>While only my name is featured on the title page of this thesis, it reached its final stage with the guidance and support of many others. I thank my primary supervisor, Ann Bremander and James Parker whom, with their professional guidance, helped complete this thesis.</p>