The required number of trials for biomechanical analysis of a golf swing

Abstract

The increasing interest in the biomechanical analysis of the golf swing warrants establishing the minimum number of trials required to obtain reliable data. Several such methods have been suggested previously for other movement tasks, and it has been shown that the number of required trials depends on the method used and on the task examined. This study aimed to compare three methods of reliability; a sequential average, intraclass correlations, and a modified version of the standard error of measurement (SEM ind). Kinematic and kinetic data of ten recreational golfers performing fifteen shots with both a six-iron and a driver was collected using a ten-camera motion capture system and force platforms. Range-of-motion, velocity, joint moments, and ground reaction forces were extracted and analysed using the three methods. The sequential average method yielded the highest number of required trials (12), while the intraclass correlations and SEM ind both resulted in lower numbers of required trials (4). Considering the variability between subjects and strengths and limitations of the various methods, we conclude that 8 trials is sufficient for biomechanical analyses of a golf swing and recommend the SEM ind method for determining how many swings should be collected.

Test–Retest Reliability of Task Performance for Golf Swings of Medium- to High-Handicap Players

“…The driver was selected because it is one of the golf clubs most frequently used both by practitioners of the sport and in studies [ 5 , 6 , 7 , 8 ]. The six iron was selected because it is an intermediate iron and is also used in studies that carry out this type of analysis [ 22 ]. At the beginning of the first session, the subjects were informed about the study on arrival and signed the informed consent form.…”

“…“Good” shots were self-determined by the participants in accordance with their perception and assessment. Any trial that the participant reported to be a miss hit or considered unsatisfactory in any other way was excluded from the analysis [ 22 ]. The participants used their own clubs during the tests and were allowed 30–60 s of rest between trials.…”

“…These parameters were computed using the first trial from the test and retest days, as well as the mean value from 2 to 15 trials in the two testing sessions. This procedure has been performed previously to determine the number of shots needed to reach acceptable reliability values for swing biomechanical variables [ 22 ]. ICC scores lower than 0.5 were interpreted as poor, those between 0.5 and 0.75 as moderate and those between 0.75 and 0.9 as good, while scores greater than 0.9 were interpreted as excellent reliability [ 26 ].…”

“…The number of swings completed in the measurement protocol is another key factor. There are several studies (not only on golf swing) that have analyzed the effect of the number of trials performed in the experimental protocol on the test–retest reliability [ 22 , 23 ]. With this analysis, reliability studies can provide recommendations on the number of trials required to carry out a reliable measurement.…”

“…As far as the authors are aware, only one study has examined the effect of the number of shots used to compute biomechanical variables related to golf performance on reliability [ 20 , 22 ]. Severin et al performed a reliability study that established the number of trials required to achieve good reliability based on the ICC, standard error of the measurement and sequential averaging analysis in low- to medium-handicap players (i.e., 7.8 ± 4.7) using a six iron and a driver [ 22 ]. The results showed that the number of trials required needed to measure range of motion, angular velocity, ground reaction forces and torques during the golf swing varied from 4 to 11.…”