2025 — The Effect of Increased Strength on Ball Release Speed and Front Foot Contact-Phase Technique

Research theme

The most recent paper in the cluster, and the peer-reviewed answer to “does strength make you faster?” It is also the paper that most directly challenges a coaching orthodoxy.

The setup: everyone assumes strength is the enabler of the known optimal technique — that a stronger bowler can hold a straighter front leg, get more trunk flexion, delay the bowling arm longer. Nobody had tested that, because you cannot isolate strength experimentally. So: use ten individual-specific forward-dynamics models, raise strength, re-optimise, and see whether the technique moves towards the known optimum.

It did not. It moved the other way.

Method, plainly: take the ten individual-specific 16-segment planar torque-driven models built, evaluated and optimised in Felton et al. (2023), and optimise each under three strength conditions: (1) the bowler’s original measured strength; (2) +5% lower body (ankle, knee, hip only); (3) +5% lower body + shoulder (ankle, knee, hip and shoulder). Strength was raised by increasing the peak isometric torque parameter (and its associated series elastic stiffness) inside the nine-parameter maximum-voluntary-torque function, so the increase applied uniformly across the joint’s whole angle and angular-velocity profile. 112 parameters re-optimised per bowler per condition on a high-performance computing system. Analysis: repeated-measures one-way ANOVA with post-hoc paired t-tests (Bonferroni-adjusted p < 0.016), SPSS for discrete parameters, SPM1D for continuous, Cohen’s d.

Elbow strength was not increased because the joint was in hyperextension and outside the active torque range for all bowlers during this phase. Wrist strength was assumed sub-maximal before release. Initial centre-of-mass position and velocity were held constant at each bowler’s fastest recorded delivery, deliberately, so that the effect of strength on technique could be isolated.

What they measured

• How fast the ball leaves the hand (ball release speed, m/s).
• How long the phase lasts (front foot contact → ball release, ms).
• Six ground reaction force parameters (peak horizontal and vertical force, BW; horizontal and vertical loading rate, BW/s; horizontal and vertical impulse, BW·s).
• Nine joint angle time histories: trunk orientation, front ankle, front knee, front hip, rear hip, front shoulder, bowling shoulder, bowling elbow, bowling wrist.
• Six joint torque time histories: front ankle, front knee, front hip, rear hip, front shoulder, bowling shoulder.
• Two ground reaction force time histories: horizontal and vertical.
• Whether any bowler’s range of motion limits were reached (range-of-motion penalties, and elbow hyperextension against each bowler’s individual limit).

Findings

Causal within the model; ten bowlers; three conditions.

1. Ball speed rose, by a little. Original 40.7 ± 1.6 m/s → lower body 41.3 ± 1.8 m/s → lower body + shoulder 41.5 ± 1.8 m/s; ANOVA p < 0.001. Post-hoc: original vs lower body p = 0.003, d = 0.36; original vs lower body + shoulder p < 0.001, d = 0.47; lower body vs lower body + shoulder p = 0.024, d = 0.11. In percentage terms: +1.5 ± 1.0% for lower body, +2.0 ± 1.0% for lower body + shoulder. Effect sizes are small (0.2 < d < 0.5).

2. Almost nothing else changed. Phase time 102 → 101 → 101 ms (p = 0.055). Peak horizontal force p = 0.458; peak vertical force p = 0.249; horizontal loading rate p = 0.283; vertical loading rate p = 0.415; horizontal impulse p = 0.387. The only significant kinetic difference was vertical impulse (0.294 → 0.292 → 0.286 BW·s, ANOVA p = 0.023), with the post-hoc difference only between the two extreme conditions (0.294 vs 0.286, p = 0.028, d = 0.140). The authors attribute even that to the near-significant reduction in phase duration, since impulse is a function of time.

3. No joint angle time history differed significantly between any of the three conditions. The only significant continuous difference was in the bowling shoulder joint torque: the increased lower-body+shoulder condition employed greater extensor torque between 53% and 61% of the front foot contact phase.

4. The headline finding — the technique adaptations ran the wrong way. Though non-significant, the post-hoc t-scores showed the increased-strength techniques exhibited:

   • less knee extension (a more bent front leg)
   • reduced trunk flexion
   • greater shoulder extension (bowling shoulder initially delayed longer but then extending further by release)

   The paper states these are “contrary to expectations” and “contrary to previous research which has associated increased ball release speeds with greater trunk flexion and less bowling shoulder extension (greater delay in arm circumduction) at release (Felton et al., 2023; Worthington et al., 2013a).”

5. The proposed explanation. Ball release speed depends on whole-body momentum available in the phase, which comes from (a) linear momentum carried in at front foot contact and (b) muscular momentum generated during the phase. As total momentum rises, the phase shortens below 100 ms, leaving less time to add muscular momentum. Because initial linear momentum was deliberately held constant in this study, the only route left to the optimiser was to generate more muscular momentum — and it did so by slowing trunk flexion and using less-extended front leg kinematics to buy the shoulder more time to work. “It is proposed that increased lower limb strength helps facilitate greater muscular contributions to ball release speed from the upper body by slowing trunk flexion and creating more time for the upper body (shoulder) to work.”

6. The direct coaching challenge. “These findings, therefore, may challenge coaching assumptions that increased strength is correlated with a more extended front leg, increased trunk flexion, and a greater delay in shoulder extension.” And in the conclusion: “Caution is advised when considering using strength interventions to alter the front foot contact-phase technique.”

7. The scale comparison. The 2.0% from a 5% strength increase is “significantly smaller than the 13.5% increase when the bowlers’ current techniques with their original strength were optimised”. Conclusion: lower body and shoulder strength are unlikely to be a major limiting factor on ball release speed or front foot contact technique in elite male fast bowlers — most probably because the ECB S&C block these bowlers had just completed already prepared them adequately for this phase’s demands.

8. A new injury warning. No range-of-motion penalties were incurred, but “most of the increased strength optimisations maximised the individualised limit for elbow extension” — i.e. the stronger models pushed elbow hyperextension to each bowler’s ceiling. Repeated elbow hyperextension has been linked to posterior elbow impingement and bone stress injuries (McBride et al., 2021). The authors therefore raise a potential link between increased bowling shoulder angular velocity and greater elbow hyperextension, and warn that “interventions focused on increasing shoulder strength and bowling arm velocity could lead to technique adaptations which elevate the risk of posterior elbow impingement and bone stress injuries.”

9. Why the field literature is contradictory — a proposed reconciliation. Real intervention studies disagree: Callaghan et al. (2021) and Hislen et al. (2023) found no ball-speed gain; Taliep & Maker (2021) and Feros et al. (2020) found gains (Feros also finding reduced accuracy). The authors argue the small effect sizes here explain it: a 5% strength gain buying ~2% of ball speed is easy to miss in an underpowered, uncontrolled, whole-body training study.

10. The 5% increase is defended as conservative but appropriate, because participants had just completed an ECB elite strength block; a similar intervention has produced ~9% average lower-limb strength gains in elite academy bowlers (Callaghan et al., 2021).

What a coach should look for on video

This paper supports no new positive technique cue. Its value is corrective, and a coach should take three things from it.

1. Do not use strength training to change front foot contact technique. This is the paper’s explicit conclusion. The common assumption — get stronger and you will hold a straighter front leg, fold further, delay the arm longer — was tested and the model trended the opposite way on all three counts. If you want the landing position and the movement sequence changed, coach them directly.

2. Recalibrate the size of the prize. 5% more strength at four joints = 2.0% ball speed in this model. Optimising landing position and movement pattern = 13.5%. For an elite male bowler already in a professional S&C programme, technique is roughly seven times the lever that this strength manipulation is. That does not make strength work pointless — it remains essential for injury resilience and for the earlier phases of the action, and the authors say so — but it is not the speed route at this level.

3. A genuine screening cue does come out of this paper — an injury one.

• The cue: Does the bowling elbow bend back past straight, and how far?
• Camera view + frame: Behind-the-arm or side-on, high frame rate (240 fps minimum), scrubbing from upper arm horizontal to ball release. Look for the forearm passing beyond the line of the upper arm.
• What “good” looks like: Hyperextension well within the bowler’s habitual range, and stable over a season.
• What the fault looks like: Hyperextension visibly at or near the bowler’s anatomical ceiling every delivery — particularly in a bowler who has recently added shoulder strength or arm speed and whose elbow now bends back further than it used to.
• Why it matters: In this study most increased-strength optimisations drove elbow hyperextension to each bowler’s individual limit. Combined with the literature linking repeated hyperextension to posterior elbow impingement and bone stress injury, this makes elbow hyperextension a monitoring variable after a shoulder-strength or arm-speed intervention. The authors label it a potential link requiring further investigation — treat it as a watch item, not an established risk factor.

Explicitly not supported:

• That stronger bowlers land with straighter front legs. No significant knee kinematic difference; the trend was towards less extension.
• That strength increases front-foot ground reaction forces or loading rates. Five of six kinetic parameters non-significant; the sixth (vertical impulse) decreased, and is attributed to a shorter phase.
• Any application to junior, club, adolescent or female bowlers — the authors flag all three as unknown and note evidence that gender-related constraints may alter optimal technique for female bowlers.

Caveats and limits

• This is a simulation, not a training intervention. Nobody in this study lifted a weight or bowled a ball faster. The “+2.0%” is a parameter change in ten computer models. This is the most important caveat in the file.
• n = 10 male ECB elite fast bowling group members (age 20.7 ± 2.4 y; height 1.91 ± 0.08 m; mass 86.9 ± 8.5 kg). The authors state that limited statistical power “may be the reason for a lack of significant kinematic differences observed” — so the “contrary to expectations” trends are non-significant trends, and should be read as a warning against the orthodoxy rather than as proof of the reverse.
• The most important design decision: initial centre-of-mass velocity at front foot contact was held constant. The authors acknowledge that in reality “an increase in strength is concurrent with an increase in centre of mass velocity at the front foot contact”, and suggest future work combining increased strength with increased approach speed. A real stronger bowler might simply run in faster and get their gain that way — a route this study excludes by construction. This substantially limits how far the “strength doesn’t help much” message should travel.
• Isometric strength only, scaled uniformly at 5%. No power, rate of force development, elastic/stretch-shortening qualities. The wrist was not strengthened; the elbow could not be.
• Front foot contact phase only. Strength’s contribution to the run-up, back foot contact, delivery stride and follow-through — and therefore to a bowler’s ability to arrive in the optimal landing position — is entirely outside the model.
• Planar (2D) model; single-parameter-set optima with robustness untested.
• Elite males only, freshly conditioned. The result is “these athletes are already strong enough for this 0.1 s”. The authors state it remains unknown how strength affects technique in populations with lower baseline strength, and whether strength interventions might produce greater gains than technique work in those populations.

Relationship to other Felton work

• Uses the ten individual-specific models built, evaluated and optimised in Felton 2023 — optimal initial position and technique for the front foot contact phase; the 40.7 ± 1.6 m/s optimised condition is the baseline.
• Uses the model developed and validated in Felton 2020 — optimising the front foot contact phase.
• This is the journal version of Felton 2024 — effect of increasing isometric strength on technique — and it disagrees with it.
• Answers, at group level, research question Q3 of the PhD Felton 2015 — PhD thesis: factors limiting fast bowling.

CONTRADICTION: (this paper reverses its own conference version) The 2024 ISBS paper, using the same ten models and the same 5% manipulation, concluded that increased isometric strength “facilitates a greater delay in the timing of bowling arm circumduction” — strength reinforcing the known optimal technique. This journal paper reports that no joint angle time histories differed significantly, and that the non-significant trends were less knee extension, reduced trunk flexion and greater shoulder extension at release — explicitly labelled “contrary to expectations” and “contrary to previous research”, with a closing warning against using strength interventions to change front foot contact technique. The conference finding does not survive peer review. Use this paper.

CONTRADICTION: (the numbers changed between conference and journal) the 2024 conference paper reports 5% strength at ankle, knee, hip and shoulder → 40.7 → 41.1 m/s (+0.8%). This paper reports the nominally identical manipulation → 40.7 → 41.5 m/s (+2.0%), with a lower-body-only condition at 41.3 m/s (+1.5%). Neither journal figure matches 41.1 m/s. The discrepancy is not acknowledged.

CONTRADICTION: (with the thesis and early conference papers) the PhD and the 2015/2017 conference papers reported that a 5% strength increase let the single bowler keep the front leg straighter, delay trunk flexion and produce more front arm extension — and that “the optimal technique remained the same”. This paper, across ten bowlers, found the trend running the opposite way on front leg extension and trunk flexion, and concluded that strength may lead to technique alterations that are contrary to the known optimum. The direction of Felton’s own strength conclusion has flipped between 2014 and 2025.

TENSION: (elbow hyperextension: speed source or injury pathway?) Felton 2016 — the effect of elbow hyperextension on ball speed frames hyperextension as an unambiguous, ICC-legal speed advantage worth ~0.2% per degree, ~5% at 20°. This paper observes that increased strength drove hyperextension to every bowler’s individual ceiling and warns of posterior elbow impingement and bone stress injury risk. The cluster contains both messages and never reconciles them.

TENSION: (no field test, ever) across the whole cluster, no Felton paper reports a real strength training intervention on real bowlers, or a real technique intervention on real bowlers. Every performance number is simulated. The 2017 conference paper promised that the model’s recommendations “will be used to shape the future coaching of this individual” and that the results would be analysed — no publication in this cluster reports that follow-up. The cluster’s central claim (technique change is worth 10–22%, strength is worth 1–2%) has never been validated by making bowlers change and measuring what happened.