Ask most golfers what determines how far the ball goes and they’ll say the same thing: swing faster. And they’re not wrong — clubhead speed is the single biggest lever you can pull. But if clubhead speed were the whole story, every golfer who swings at 105 mph would carry the ball 280 yards. They don’t. The gap between swing speed and actual carry distance is where most amateur performance is lost, and it’s a gap that a launch monitor can make visible. This winter has been especially cold in Connecticut, so this is a perfect time to head to a place with a Trackman (like Golf Lab CT) before getting ready to face the especially long par 5s at Oxford Greens (like the 630-yard monster on hole #3)
A 2023 paper published in the Strength and Conditioning Journal by Brennan and colleagues — researchers from Middlesex University, the DP World Tour Performance Institute, Columbia Business School, and the R&A — mapped out a deterministic model of the golf shot, tracing exactly how impact factors at the clubface cascade through to the launch characteristics of the ball and finally to the outcome measures of distance and accuracy. Their framework is the clearest summary of launch monitor science I’ve encountered, and it has practical implications for any golfer using TrackMan or a similar system.
This article translates that research into actionable guidance: what to measure, what it means, and how to use it to add real carry yards without rebuilding your swing.
The Outcome That Actually Matters: Strokes Gained
Before diving into mechanics, it helps to understand what “better” means in quantitative terms. The metric that best captures driving performance is Strokes Gained Off the Tee (SGOTT), a framework developed by Mark Broadie — one of the paper’s co-authors — and now used by the PGA Tour for all tournament statistics.
Strokes gained measures how many strokes a player gains or loses on a given shot relative to the field, based on where the shot started and where it finished. Broadie’s research found that the long game — tee shots and approach shots — accounts for approximately 72% of the variability in a PGA Tour player’s overall skill. Distance matters: an extra 20 yards off the tee is worth roughly 0.75 strokes per round. That’s a meaningful advantage over a full season.
But strokes gained requires knowing shot location data typically only available during competition. For training purposes, the launch monitor metrics described below are the proxies that practitioners and golfers can actually work with — the upstream causes that feed into SGOTT.
The Distance Chain: From Impact to Carry
Brennan et al. describe shot distance as the product of a chain of causes. Understanding the chain tells you where to intervene. Here are the five variables that matter most.
1. Ball Speed — The Master Metric
Ball speed is the velocity of the ball’s center of gravity immediately after it separates from the clubface. It is the most direct predictor of carry distance: research shows that each 1 mph increase in ball speed produces approximately 1.83 yards of additional carry (Betzler et al., 2014). Ball speed is what you should optimize, not clubhead speed in isolation.
Clubhead speed explains 75% of ball speed variance on its own, but that rises to 82% when impact location is also accounted for (Sweeney et al., 2013). The difference between those two numbers — that extra 7% — is the efficiency gap that most amateur golfers have available to them without changing their swing speed at all.
2. Impact Location — The Efficiency Variable
Impact location refers to where on the clubface the ball makes contact, measured in millimeters from the geometric center both vertically and horizontally. Striking off-center triggers the “gear effect” — the clubhead rotates around its center of gravity, altering spin characteristics and reducing ball speed.
Off-center strikes to the toe produce right-to-left spin (draw spin for a right-hander). Off-center strikes to the heel produce left-to-right spin. Strikes high on the face reduce backspin; strikes low on the face increase it. All of these alter trajectory in ways that reduce carry distance even at identical swing speeds. This is why smash factor — the ratio of ball speed to clubhead speed — is the most actionable consistency metric on TrackMan. A smash factor of 1.50 is the theoretical maximum with driver; most recreational golfers average closer to 1.40–1.44. Closing that gap is free distance.
3. Spin Rate — The Optimization Variable
Backspin creates lift by acting perpendicular to the ball’s flight path, counteracting gravity and keeping the ball airborne longer. The problem is that excessive spin also increases drag and causes the ball to balloon, which reduces carry. Spin rate has an optimal range — it is not a case of more being better.
Wallace et al. found that driver spin rates between 2,280 and 2,640 rpm maximize carry distance for elite players. Brennan et al. note that PGA Tour and LPGA Tour averages sit at approximately 2,685 and 2,682 rpm respectively — slightly above the theoretical optimum, suggesting that even tour players carry marginal spin inefficiency. For recreational players, spin rates of 3,200–3,800 rpm are common, which can represent a carry loss of 15–25 yards compared with an optimized spin profile at identical swing speeds. Spin rate is influenced by clubhead speed, vertical impact location, angle of attack, and dynamic loft — all of which are measurable.
4. Launch Angle — The Trajectory Variable
Launch angle is the vertical angle of the ball’s initial flight relative to the ground. Too low and the ball doesn’t stay airborne long enough to maximize carry. Too high and it balloons, generating excessive spin and losing distance. The research-supported optimal range for driver is 10–14 degrees for elite golfers, though some studies suggest up to 20 degrees can maximize carry distance under specific conditions.
TrackMan University data provides a useful calibration point: a golfer swinging at 95 mph with a +4-degree attack angle (hitting up on the ball) should target a launch angle of 15.6 degrees and a spin rate of 2,404 rpm to maximize distance. The same 95 mph swing with a -4-degree attack angle (hitting down) should target 11.4 degrees launch and 3,150 rpm. Attack angle affects both launch angle and spin simultaneously, which is why sweeping the driver off the tee — with a slightly positive attack angle — tends to optimize both variables at once. Launch angle is strongly correlated with dynamic loft (r = 0.74).
5. Dynamic Loft — The Loft You Actually Deliver
Dynamic loft is the vertical orientation of the clubface at the moment of maximum compression — the effective loft delivered to the ball, which is often quite different from the club’s stated loft. Dynamic loft is the primary driver of launch angle (b = 0.58) and contributes meaningfully to spin rate. If dynamic loft is too high, backspin increases and distance suffers. If too low, the ball launches too flat.
Increasing your attack angle with driver — hitting slightly up on the ball — reduces dynamic loft relative to the club’s physical loft, which is why it typically produces both lower spin and higher launch. The combination of positive attack angle and appropriately matched dynamic loft is the driver fitting formula that launch monitors were designed to optimize.
Launch Monitor Reference: Key Distance Metrics
This table summarizes the five core distance metrics, their optimal ranges for driver, and what to do if your numbers are outside those ranges.
| Metric | Optimal Range (Driver) | If Too Low | If Too High |
| Ball Speed | 150–175+ mph (varies by CHS) | Improve center contact; raise CHS | N/A — maximize this metric |
| Smash Factor | 1.48–1.50 with driver | Focus on strike quality; find sweet spot | Theoretical max is 1.50; maintain it |
| Spin Rate | 2,280–2,640 rpm (elite) | Check impact location & dynamic loft | Positive attack angle; less dynamic loft |
| Launch Angle | 10–14° (up to 20° in some models) | Increase attack angle; raise dynamic loft | Reduce dynamic loft; check tee height |
| Attack Angle | +2° to +5° with driver | Tee ball slightly higher; widen stance | Ball position adjustment; check setup |
Shot Dispersion: Why You Miss Offline
Distance and accuracy are not independent variables — they share several upstream causes. Brennan et al. dedicate equal attention to shot dispersion, which is the lateral accuracy of the shot measured as how far offline the ball finishes relative to the intended target.
Two launch characteristics govern dispersion: spin axis and launch direction. Both are primarily controlled by face angle at impact — the single most powerful accuracy variable in the golf swing.
Spin Axis and the D-Plane
The spin axis is the tilt angle of the ball’s rotational axis immediately after impact. When the spin axis is tilted, the ball curves. TrackMan reports that for every 5 degrees of spin axis tilt, the ball will deviate 3.5 yards per 100 yards of ball flight — meaning a 280-yard drive with a 10-degree spin axis tilt finishes approximately 20 yards offline.
Face angle at impact explains 82% of spin axis variance (Miura, 2002). Club path influences spin axis as well but to a lesser degree. The relationship is described by the D-Plane theory: the ball’s initial direction is primarily determined by face angle, and the curve is determined by the relationship between face angle and club path. A face angle pointed right of path produces left-to-right spin (fade/slice); left of path produces right-to-left spin (draw/hook).
Face Angle and Launch Direction
Launch direction — the horizontal angle at which the ball departs the clubface — is explained by face angle up to 61–83% of the time (Wood et al., 2018). The practical implication is significant: Sweeney et al. found that a 2-degree error in launch direction with driver produces approximately 10 meters of offline distance at 280 meters of carry. The same 2-degree error with a 120-meter wedge produces only 4 meters of offline deviation.
This explains why driver accuracy is so disproportionately affected by small face angle errors compared with shorter clubs. The amplification of face angle errors with driver is one reason why many golfers should prioritize face control work before obsessing over swing path.
A Practical TrackMan Monitoring Protocol
Brennan et al. emphasize that monitoring variability in these metrics — not just peak values — is essential for practitioners and golfers using launch monitors. They recommend establishing baseline scores for key metrics, then using the coefficient of variation (CV) to set targets for meaningful improvement. Here is how to apply that framework in a practical TrackMan session.
Session Structure by Week
| Week | TrackMan Session Focus | Shots |
| 1 | Baseline only. 20 drivers at normal intent. Record mean and SD for ball speed, smash factor, spin rate, launch angle. No swing changes. | 20 |
| 2 | Identify primary fault. If smash factor < 1.44: impact location work. If spin > 3,000 rpm: attack angle and tee height drills. If launch < 10°: dynamic loft assessment. | 20 |
| 3 | Targeted intervention. Use feedback from Week 2 to address single variable. Hit 15 balls per session tracking only the target metric. | 15 |
| 4 | Validation session. Repeat Week 1 protocol exactly. Compare mean and SD across all metrics against baseline. Look for co-improvement in related metrics. | 20 |
| 5–6 | Integration. Hit shots without deliberate mechanical focus. Allow adaptations to consolidate. Monitor carry distance and dispersion as outcome measures. | 20–25 |
Key Metrics to Track — What Improvement Looks Like
- Ball Speed SD: Target variability of ±5 mph or less across a 20-ball session. Wild swings indicate inconsistent strike or tempo.
- Smash Factor: Each 0.01 improvement in average smash factor is worth approximately 1.5 mph of ball speed without changing swing speed. Target 1.47+ as an intermediate golfer.
- Spin Rate: For most recreational players, reducing spin from 3,200 to 2,700 rpm (through attack angle and tee height adjustment) can add 12–18 yards of carry at identical swing speeds.
- Launch Angle: Should be within 1–2 degrees of your optimal value across a session. Large variance in launch angle indicates inconsistent dynamic loft delivery.
- Carry Distance SD: This is the final proof. Brennan et al. suggest using the CV to set targets — a CV of 5% on driving distance means your carry must improve by more than 5% before the change exceeds measurement noise.
A Note on Skill Level and Metric Usability
Brennan et al. make an important practical point that often gets overlooked: the usability of some metrics depends on a golfer’s skill level. A professional golfer can produce reasonably consistent clubhead speed and distance on demand. A 18-handicapper may show consistent clubhead speed but far more variable carry distance — because the ability to transfer speed consistently into ball speed requires a level of strike quality that develops over time.
This means that recreational golfers should probably focus first on smash factor and spin rate consistency before chasing raw ball speed gains. A 95 mph swing hitting 1.47 smash factor will outcarry a 100 mph swing hitting 1.39 smash factor every time. Get the efficiency right first; the speed gains will layer on top.
Final Word
TrackMan and comparable launch monitors are now available at most Connecticut simulators and indoor facilities, typically included in the hourly bay rate. The information they provide is only useful if you know what to look for. Brennan et al.’s deterministic model gives you the map: ball speed drives carry distance, and ball speed is determined by clubhead speed multiplied by strike efficiency. Spin rate needs to be optimized, not maximized. Launch angle needs to match your attack angle and dynamic loft. Face angle governs dispersion.
None of this requires a swing overhaul. Impact location, attack angle, and tee height are all adjustable without mechanical reconstruction. A single focused TrackMan session — baseline numbers, identify the primary fault, set a target — is more likely to improve your driving distance than another bucket of balls hit without feedback.
Clubhead speed matters. But as Brennan and colleagues make clear, it’s only the beginning of the chain. The golfers who close the gap between potential distance and actual distance are the ones who understand the links between impact and carry — and work on them methodically.
Source: Brennan A, Ehlert A, Wells J, Broadie M, Coughlan D, Turner A, Bishop C. Monitoring Performance in Golf: More Than Just Clubhead Speed. Strength and Conditioning Journal. 45(6):631–641, December 2023.
David is an avid golfer who loves walking Connecticut’s courses and playing alongside his family. He’s passionate about golf course architecture and one day hopes to play at Pebble Beach.
