Discussion

The primary aim of the present study was to provide a comparison of two training interventions on University male and female golfers: one which focused on S&C training only, and one which focused on S&C in addition to maximal swing speed training. When focused on within-group changes, the CONTROL group elicited no significant changes from pre to post, whilst the SWING group showed significant improvements in eight test measures, but also one significant reduction as well. When focused on between-group differences, results showed that the SWING group elicited significantly better improvements in one golf shot measure and two physical capacity measures. In contrast, the CONTROL group showed significantly superior results for CMJ peak power.

When focusing on within-group effects, the SWING group showed significant improvements in a total of eight test measures. Most importantly though, was a large improvement in smash factor (g = 1.68), despite the absolute change being an improvement of only 0.02 and a small reduction in CHS (g = -0.37). There may be two viable reasons for why this change was evident. Firstly, and as outlined in the methods, smash factor is a ratio metric that divides ball speed by CHS and serves as a measure of ‘efficiency of strike’.^2,23 In essence, although CHS had a small reduction, the increase in ball speed was proportionally greater, having a more pronounced effect on the resultant smash factor value. Related to this, the SD for smash factor was also very small at both time points, which has a material impact on the 95% CI values, which in turn, also enabled statistical significance to be reached and for the change to still be greater than the baseline measurement error (CV = 0.66%). Second, it seems plausible to suggest that practicing swinging the club as fast as possible may allow players an ability to control the club better at comparable swing speeds (noting that the absolute mean reduction in CHS was only 0.32 mph). Put simply, despite no positive change in CHS being evident, a player’s ‘maximal swing speed ceiling’ may have increased, enabling better control of the club at impact. This seems like a viable explanation, given ball speed, carry distance and smash factor all showed improvements. It also highlights more than one credible way to make improvements in distance i.e., chasing increases in CHS is of course desirable, but impact location on the clubface is also of material relevance.⁸

From a physical capacity perspective, both the medicine ball throw for distance and thoracic spine mobility tests (on both sides) showed significant increases. Whilst the S&C programming was more focused on the development of maximal and ballistic force production in both the lower and upper body (Table 1), there is some element of kinematic similarity in these tests to the golf swing. Further to this, previous associative^9,10,20 and intervention-based research^3,17 in golf, has shown the importance of ballistic force production in the upper body, in a rotational manner. Thus, the inclusion of maximal swing speed training may have had some carryover to improvements in kinematically similar physical capacity tests. This theory is also supported in the present study’s findings by a significant improvement in force at 200 ms during the isometric bench press (g = 0.46); another ballistic force production measure. Whilst the significant reduction in force at 100 ms in the same test goes against this theory, it should be noted that force at 100 ms showed a significant worsening of absolute reliability post-intervention (CV pre = 5.06%; CV post = 12.81%). This would indicate substantially less consistency between trials during post-testing procedures for this metric and when the average of all trials is used (as opposed to the best score), this may have contributed to the significant reductions seen at the post-testing time point. Finally, it was also encouraging to see significant improvements in the isometric squat test as well, given previous research has heavily championed the importance of maximal and ballistic force production in the lower body,^2,9,17,23,25 due to the proximal-to-distal sequencing pattern of the golf swing.

When focused on the CONTROL group, initially it seems concerning that there are no significant changes in any test, not even for physical capacity measures. However, there are a couple of finer points to consider here. Firstly, the sample size in this group is smaller and although only one participant smaller, it seems that this may have had a material impact on whether post-testing scores reached statistical significance. Specifically, with an already small sample for the SWING group (n = 6), the one less participant for the CONTROL group further widened the lower and upper boundaries of the 95% CI (and this directly relates to the second point of consideration). If we consider mean effects for CHS and CMJ peak power, we can see that large improvements were evident, with Hedges g values of 0.85 and 1.37, respectively. Consequently, although we cannot do anything about the sample size in the present study, these data do highlight the relevance of reporting and monitoring practically relevant changes in the form of ES, a notion championed for this very reason in a recent S&C intervention in University-level male and female golfers.³

When focused on the between-group changes, and without focusing on whether statistical significance was reached for a moment, five differences favoured the CONTROL group and 12 favoured the SWING group. Of those, a total of four measures showed significant between-group differences and at this point, readers should note that these differences are merely a reflection of both sets of within-group changes. Importantly, smash factor showed a very large benefit favouring the SWING group (g = 2.31), indicating that efficiency of strike is likely to be positively impacted from including micro-dosed maximal swing training, rather than not doing any at all. That said, a closer inspection of Figure 3 indicates that the change in smash factor was almost exclusively driven by two players, so some degree of caution should be applied to these changes. Interestingly as well, CMJ peak power favoured the CONTROL group (g = -1.98). However, this is not so much a consequence of a meaningful reduction in the SWING group, as it is a large improvement in the CONTROL group. In addition, with such a large improvement in medicine ball throw for distance on the left side for the SWING group (g = 2.24), the knock-on effect was a significant between-group difference for this measure as well (g = 1.83). Given all golfers in the present study were right-handed, this expression of ballistic force production ‘to the left’ in a rotational manner, is something that all players are used to, which may have had an impact on the difference seen between groups for this measure.

There are a number of limitations that should be acknowledged in the present study. Firstly, the sample size was small and this is something that is not uncommon in performance science literature in golf. We have attempted to ensure that the key messages are conveyed within the context of this limitation, by recognising the importance of presenting ES data, alluding to the relevance of the 95% CI and SD – key parts of understanding magnitudes of change, and also showing some individual data in Figure 3. Second, a recent S&C-based intervention in golf highlighted the importance of running interventions that last longer than 8-weeks,³ and sub-group analysis in a systematic review for golf has also alluded to this point.¹⁷ Thus, some degree of caution should be applied to our findings, not only because of the sample size, but because of the intervention duration. Unfortunately, this was unavoidable as players went off to compete in international tournaments soon after the intervention period. Lastly, both groups contain a mix of male and female players. Whilst this is not a limitation in its own right, previous research has shown large discrepancies in many of these test measures between male and female golfers¹³; thus, it is plausible that some of the within and between-group changes were impacted by homogeneity issues in the groups.

Practical Applications

Based on the findings in the present study, and notwithstanding the issues around sample size, maximal swing speed training does show improvements in golfing proxy measures. Whilst the exact mechanisms cannot be established, it seems sensible to suggest that the accumulated effects may help to push a player’s ‘CHS ceiling’, so that comparable swing speeds can be better controlled at ball impact. As such, our message here is that micro-dosing this part of a golfer’s conditioning during practice sessions on the range, is a viable strategy to accumulate volume (and therefore adaptation) over time.¹⁴ Additionally, if golfers are not used to this type of training, we have two anecdotal suggestions: i) start maximal swinging with your own driver and there is no need to focus on even hitting a golf ball, and ii) build volume slowly. This latter suggestion comes from a place of understanding that the golf swing produces approximately eight times a player’s body mass in rotational torque on the spine.¹⁵ Thus, attempting to swing the club as fast as possible will almost certainly increase the stress placed on this part of the body, which is a commonly injured area in golfers.²⁴ As such, the notion of accumulating volume for maximal swing speed training should be done carefully, and players and coaches should accept that adaptations from this part of a player’s conditioning programme may take time and are likely to plateau eventually. However, when this form of training is undertaken in conjunction with strength and power training, it seems logical to suggest that improvements in swing speed may come from a variety of different training modalities.

Correspondence:
Name: Chris Bishop
Email: C.Bishop@mdx.ac.uk
Address: London Sport Institute, Faculty of Science and Technology, MIddlesex University, UK

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