Exercise Intensity and Activity Energy Expenditure of Professional Golf Players in Official Competitive Setting

Abstract

Background:

Research regarding the physical needs of professional golf players is lacking. With advances in wearable technology, it has become easier to analyze physiological responses such as heart rate (HR) to determine activity energy expenditure (AEE). The purpose of the study was to evaluate exercise intensity (EI) and AEE during 4 consecutive tournament’s golf rounds using a popular wrist-based HR monitoring.

Hypothesis:

Wearable systems for HR monitoring can be used to provide an accurate estimate of energy expenditure.

Study Design:

Cross-sectional study.

Level of Evidence:

Level 3.

Methods:

A total of 20 male professional golfers participated in the study. Each player was monitored during an official tournament consisting of 4 rounds of 18 holes. EI and AEE were determined using HR wrist monitoring (Whoop Strap 2.0). We calculated the percentage of HR_max (%HR_max) and the percentage of HR_res (%HR_res) and the AEE in kcal/min using Keytel’s formula.

Results:

The calculated mean %HR_max and %HR_res for the study population were 56.4% ± 1.8% and 40.5% ± 2.6%, respectively. Considering American College of Sports Medicine guidelines, these average percentages correspond to a moderate EI. The average caloric expenditure was 5.4 ± 0.4 kcal/min and 1555.8 ± 157.8 kcal per round considering an average golf round duration of 288.3 ± 19.5 minutes.

Conclusion:

A professional player’s golf round is moderate physical activity. The AEE of this activity was equal to 5.4 cal/min, which is moderate energy consumption.

Clinical Relevance:

These data could help golf coaches and conditioning coaches to have a better understanding of the load placed on golfers during tournaments.

Golf is a very popular sport all over the world, whether it is played for recreation or competition; however, research regarding the physical needs of professional golf players is lacking.^{15,19,24,34,41}

Professional golf is physically demanding; however, little study has been done to establish the exercise intensity (EI) and activity energy expenditure (AEE) during an official competition. ¹⁹ As an athlete, the golf player is subjected to varying degrees of physical exertion during a golf round, depending on the course terrain, weather conditions, and level of play, among other physiological factors.

The golf round involves very long walks, which are characterized by an energy expenditure (EE) linked to walking speed, distance, and the ascents and descents of the course. ³⁴ These walking sessions are alternated with swing sessions, which may have different technical characteristics and whose AEE is difficult to quantify due to the very short duration of the technical movement. Knowledge of the physical needs of athletes during a competition is a fundamental requirement for conditioning coaches to build a sport-specific conditioning program. ²⁴

To achieve high performance, golfers must optimize their swing mechanics to undertake the physically demanding conditions encountered during play. ³¹ Therefore, golfers should also have a moderate cardiovascular endurance, strength, power, balance, flexibility, and coordination.

Unfortunately, the evaluation of AEE on the golf course using a portable gas analysis system is not practical; therefore, it is necessary to use other ways to collect these data. With advances in wearable technology, it has become easier to gain knowledge about physical activity (PA) outside the laboratory despite their known limitations.^12,29 Wearable devices use technology to analyze physiological responses such as heart rate (HR) to determine AEE, which can be detected using a chest strap or wrist monitor. ⁵ Pulse-based HR accuracy probably works well for golf as it is a high-to-moderate intensity activity. ³⁹

Estimation of AEE and PA via HR monitoring is popular, convenient, relatively inexpensive, noninvasive, and versatile. Along with pedometers and accelerometers, HR monitors are major examples of objective measurement. ³⁰ Monitoring HR minute-by-minute enables detailed information on frequency, intensity, and duration of free-living PA. ²⁸

HR monitoring is used to estimate AEE based on the assumption of a linear relationship between HR and oxygen uptake (VO₂) during steady and nonsteady states of exertion.^7,18 Despite considerable interindividual variability in the slope of the HR-VO₂ relationship, the linear relationship is consistent for a person across a range of submaximal tasks.^13,22

A major benefit of HR data is the ability to quantify EI and estimate AEE in continuous or stationary aerobic exercise. ¹⁷ To describe EI, HR levels must be expressed as a percentage of HR reserve (%HR_res) and/or percentage of maximal HR (%HR_max) allowing EI to be classified into 6 categories from very light to maximum.^4,38

The purpose of the study was to assess EI and AEE during 4 consecutive official tournament golf rounds in a group of 20 male professional golfers using a popular wrist-based HR monitoring system already used commonly by all of them.

Methods

A total of 20 male professional golf players who competed in the Alps Tour (2021) and European Challenge Tour (2021) participated in the study. Each player was monitored during an official tournament consisting of 4 rounds of 18 holes from Thursday to Sunday on 4 consecutive days. All participants agreed and signed a written consent form before participation, and the study was approved by the Policlinico di Monza Ethics Committee. The place in the world ranking of each participant was based on the OGWR (Official Golf World Ranking, https://www.owgr.com/).

For data collection, 2 official tournaments were monitored in 2 different courses but with the same characteristics of length, terrain, and weather conditions. These 2 golf courses were included the first in the Alps Tour schedule (10 players) and the other in the European Challenge Tour schedule (10 players). All participants walked the entire distance of the course carrying their golf bags.

Anthropometric data such as height, weight, and body mass index (BMI) were measured. Basal metabolic rate was estimated using the Harris-Benedict function. ¹⁴ HR was measured using the Whoop Strap 2.0 wrist monitor. All players wore the monitor on their wrist and stated that it did not interfere with their golf swing. Only players who had been using the Whoop Strap 2.0 for at least 6 months (to familiarize players with it) were included in the study. Players who used the system positioned on the upper side of the arm instead of on the wrist were excluded. The wrist is a strong pulse point where HR can be measured accurately, and this device position was selected for its accuracy and comfort whether the player is walking or swinging.

The Whoop Strap 2.0 (Figure 1) can assess sleep quality, training effort, and recovery using HR, heart rate variability (HRV), and other metrics. ⁶ Light-emitting diodes and photoplethysmography (PPG) technology allow getting those measurements. Instantaneous HR data were represented on a graphical trend in the Whoop’s web portal. The health metrics like HRV, resting HR (HR_rest), respiratory rate, and skin temperature are measured by the Whoop’s software at the same time, which is in the last moments of sleep immediately before waking up. Instantaneous single-point HR minimum (HR_min), HR peak (HR_peak), and average HR (HR_ave) were measured for each round of 18 holes. HR measurements were performed using the proprietary software’s digital cursor. The HR_min was measured 5 minutes after the first shot (tee time) to rule out the HR stress-related increase preceding the start of the match. The HR_peak was measured in the same way by identifying the maximum peak on the HR graphical trend during playing time. The HR_ave was calculated by the formula (HR_min+ HR_peak)/2.

Figure 1.

Whoop wrist HR monitor. HR, heart rate.

Through the use of standardized formulas, we estimated the maximal HR (HR_max = 208 - (0.7 × age)) and HR reserve (HR_res = HR_max - HR_rest). Then, for each golf round, we calculated the percentage of HR_max (%HR_max= [HR_ave × 100]/HR_max) and the percentage of HR_res (%HR_res = HR_ave - HR_rest/HR_max - HR_rest × 100). Once these data had been collected, we calculated the AEE in kcal/min using Keytel’s formula: EE = gender × (-55.0969 + 0.6309 × HR + 0.1988 × weight + 0.2017 × age) + (1 - gender) × (-20.4022 + 0.4472 × HR - 0.1263 × weight + 0.074 × age) where gender = 1 for males and 0 for females. ²⁰ Since using this formula has shown an overestimation of energy consumption ranging from 28.6% to 35%,^1,29 we decided to reduce the results obtained by 31.8%, which represents the average of the AEE overestimation described above.

Results

Golfers had a mean age of 24 years (±2.6) and a mean BMI of 24.2 kg/m2 (±1); the players were essentially bradycardic with an HR_rest of 51.1 bpm (±2.8) with an age-predicted HR_max of 191.2 bpm (±1.8). The average Official World Golf Ranking was 830 (± 366), which placed them at a medium-to-high professional level. Further anthropometric and cardiac function data are shown in Table 1. Using continuous HR recording, as described above, we evaluated HR changes during golf rounds. During competition, the golfers showed an average increase in HR up to 107 ± 3.2 bpm, corresponding to 56.4 ± 1.8 of %HR_max and 40.5 ± 2.6 %HR_res, respectively, with peaks of 154 bpm. Table 2 reports the values of HR variations and EE during competition.

Table 1.

Study population characteristics

Characteristic	Mean ± SD
Players, N	20
Age, y	24 ± 2.6
Weight, kg	77 ± 4.3
Height, cm	178.3 ± 2.9
BMI	24.2 ± 1
BMR	1769.3 ± 58.5
HRmax	191.2 ± 1.8
HRrest	51.1 ± 2.8
HRres	140.2 ± 3.7
OWGR	830 ± 366

BMI, body mass index; BMR, basal metabolic rate; HR, heart rate; HR_max, maximal HR (208 – [0.7 × age]); HR_res, HR reserve (HR_max - HR_rest); HR_rest, HR at rest; OWGR, official world golf ranking.

Table 2.

HR variations and energy expenditure during professional golf rounds

Parameter	Mean ± SD
Round duration, min	288.3 ± 19.5
HRave, bpm	107.9 ± 3.2
HRmin, bpm	61.3 ± 2.8
HRpeak, bpm	154.5 ± 7.1
%HRmax	56.4 ± 1.8
%HRres	40.5 ± 2.6
AEE, kcal/min	5.4 ± 0.4
AEE, kcal/h	323.6 ± 21.9
AEE, kcal/round	1555.8 ± 157.8

AEE, activity energy expenditure; HR, heart rate; HR_ave, average HR; %HR_max, percentage maximal HR; HR_min, minimum HR; HR_peak, peak HR; %HR_res, percentage HR reserve.

Based on the %HR_max and %HR_res values achieved during exercise, American College of Sports Medicine (ACSM) guidelines classify EI as follows: low (%HRmax 45-54, %HR_res 30-39), moderate (%HR_max 55-69, %HR_res 40-59), or high (%HRmax 70-89, %HR_res 60-84).^4,38 Considering the ACSM guidelines, data reported in Table 2 for our study population correspond to a moderate EI, or rather to an EI between 4 and 6 metabolic equivalents of task (METs) or rating of perceived exertion of 12-13.^4,38

Using the modified Keytel formula,^20,29 we calculated the AEE in kcal/min. The average caloric expenditure was 5.4 ± 0.4 kcal/min and 1555.8 ± 157.8 kcal per round considering an average golf round duration of 288.3 ± 19.5 minutes.

Discussion

The main finding of this study was that the average EI of a single professional golf round evaluated by the %HR_max and %HR_res can be considered as a moderate activity according to ACSM guidelines.^4,38

Golf includes long periods of walking, and the effort of the game depends on the walking speed, the distance traveled, the design of the golf course, whether golfers carry their equipment or use a cart, and whether the cart is a push or electric cart.^9,31 Referring to the ACSM guidelines for the classification of PA intensity,^16,4 previous research indicates that the intensity of the golf round varies from low to high intensity (3-6 METs).^2,35

Quantitative studies addressing the EI and AEE of golf are lacking in the scientific literature. In relation to HR_max, Stauch et al ³⁴ found that most time during a round of golf is spent at 50% to 74% HR_max. Tangen et al ³⁶ described that 75% of a golf round is played at <70% HR_max and that 25% is at >70% HR_max. Broman et al ⁸ found that 70% of total time for elderly men is at >70% HR_max, whereas for middle-aged and younger men, most time is spent at <70% HR_max. Loy ²³ estimated that 75 minutes are >60% HR_res.

Ultimately, as described in a previous review by Luscombe et al ²⁴ in nonathlete populations, the values for %HR_max are within light (50%-63%) and moderate (64%-76%) intensity. The average round time was 227 minutes and golfers walked approximately 9000 m. Golfers spent most of their time with moderate-intensity PA: 82 minutes with 50% to 74% of HR_max. ²⁴

In a recent study by Kasper et al, ¹⁹ the mode of transporting the golf clubs had no meaningful difference in AEE, and the HR variation in players carrying a golf bag was 97 to 144 bpm (HR_ave, 120.5 bpm). In a cohort of 66 healthy subjects with large age variations and varying individual golf indexed handicaps, Zunzer et al ⁴¹ stated that EIs were moderate concerning the percentage of HR_max (60.8 ± 8.2).

In our population of professional golfers, the playing HR_ave was 107.9 ± 3.2 bpm, which represented 56.4% ± 1.8% of HR_max and 40.5% ± 2.6% of HR_res. These values allow us to include professional golf as a moderate-exercise activity.

There is, however, a large gap between HR_ave and %HR_max in playing a round of golf. This is related to temporary physical needs related to both the athlete’s body and golf itself. ⁹ In our study, the %HR_max was similar to that found in other above-mentioned studies; however, it should be noted that professional golf players had a lower HR_rest and a higher HR_max (Table 1). Being bradycardic athletes, the increase in absolute value of HR up to HR_ave during the competition was therefore greater. This can be interpreted as a major aerobic power during competition. These results are indicative of more skilled players, as these players take longer to select the correct shot and experience increased pressure and repeated practice swings before hitting the ball.^10,40

In our work, we estimated EI values for golf activity using %HR_max or %HR_res. In previous studies, %HR_res has been reported to be a major predictor for estimating EI.^2,23,32 In our study, by evaluating the functions f(x), expressions of the linear relationship between AEE and %HR_max or %HR_res, respectively, we obtained R ² values of 0.85 and 0.61 using %HR_max and %HR_res, respectively (Figure 2). These data indicate that using the Whoop HR monitor, the predictive power of %HR_max is greater than that of %HR_res to estimate AEE values.

Figure 2.

Linear relationship between AEE and (a) %HR_res and (b) %HR_max. AEE, activity energy expenditure; %HR_max, percentage maximal HR; %HR_res, percentage HR reserve

Regarding the metabolic cost, golf can be particularly onerous. For golf, metabolic rate can be calculated using the non-calorimetric method, which evaluates the amount of AEE based on physiological responses. ²¹

Studies on nonprofessional golfers show that the average nonprofessional player burns approximately 930 calories during an 18-hole round of golf. ⁴¹

Smith ³² reported higher values for total caloric expenditure in a range between 1954 kcal playing on a hilly course while carrying a bag, and 1527 kcal using a trolley. Murase et al ²⁷ found average caloric values of 960 kcal following 18 holes of golf, which was comparable with our results. However, in all of these studies, estimating VO₂ demand and extrapolating EE may have underestimated actual energy requirements. ³¹

In previous research on collegiate golfers, ¹⁵ although male golfers recorded a greater calories/hour value than female golfers, female golfers experienced greater overall tournament kcals (female golfers: 1642.33 ± 442.98 kcals; male golfers: 1583.13 ± 145.80 kcal). This is because female golfers took a longer time to complete the rounds of golf, travelled a greater distance, and had a higher HR_ave during rounds. Not only did the extended amount of time on the course increase the female players’ caloric expenditure, but it increased HR as well.

In a cohort of high-level golfers, Kasper et al ¹⁹ reported that the AEE for a round of golf was 3.4, 3.6, and 3.2 kcal/min for bag carrying, manual trolley, and electric trolley condition, respectively. Considering a round time about 205 minutes, the total round AEE was between 688 and 756 kcal, with a trivial and small effect between the transportation modes. ¹⁹

Our research using the modified Keytel’s formula indicates that the caloric consumption per minute during an official competition golf round was on average 5.5 ± 0.4 kcal,^20,29 which corresponds to a caloric consumption of 323.6 ± 21.9 kcal/h. Considering that the average working time for a round of golf was calculated as 288.3 ± 19.5 minutes, the average caloric consumption for a round of golf in the professional setting was 1555.8 ± 157.8 kcal.

In evaluating AEE, the use of a wearable HR monitor during the golf tournament testing could overestimate male golfers’ kcal expenditure, showing that there is an inaccuracy in wearable activity tracking devices. ¹⁵ Although PPG is a simple, reliable, and low-cost optical measurement technique, the accuracy of PPG activity monitors is affected by artifacts associated with sensor movement.^33,37 Hierholzer et al ¹⁵ showed that the main variable affecting the estimation of the EE was HR, leading to the belief that the wearable device does not accurately collect HR during activity. ¹⁵ These findings are supported by a statement by Albinali et al, ³ who stated there is an inaccuracy in wearable devices depending on the person’s size, fitness status, as well as placement of the device on the wrist. In our work, the population studied was represented by male athletes with similar anthropometric characteristics and the device used has design characteristics that allow a perfect placement on the wrist; in any case, all the players were familiar with the device because they had been using it for at least 6 months. There was a trivial and not statistically significant bias between Whoop-derived HR edited by Whoop’s proprietary filter and electrocardiogram-derived HR. ⁶

The second possible cause of inaccuracy in the estimate of the AEE could be found in the equation used for the calculation of AEE itself. Despite Keytel’s equation being the best performing published algorithm of its kind, it has 2 primary issues - first it was fit only to exercise conducted at an intensity of 57%, 77%, and 90% of HR_max, and is therefore untested above and below these intensities; and second it was found to explain only 73.4% of the variance in true EE. This means that a workout estimated to consume 1000 calories could have easily burnt 734 (overestimation). Since an overestimation of energy consumption ranging from 28.6% to 35% has been shown using this formula, ²⁹ we decided to reduce the results obtained by 31.8%, which represents the average of the overestimation described above.

Regarding the golf round time duration in our study, the average playing time was 288.3 ± 19.5 minutes. In the previous study, the average playing time for golfers with different handicaps ranged between 258 and 288 minutes. ²⁴ These data echo those of McGee, ²⁶ who reported a gameplay duration of approximately 4 to 4.5 hours. The study also corresponds to that of Magnusson et al, ²⁵ who reported rounds of golf lasting between 3.5 and 6 hours. Players with the best handicap scores played longer than less skilled players, because golfers with lower handicaps spend more time evaluating possible shot selections. These players also spend more time reading the green before the put, considering all possible influences on the shot. ²⁶ Furthermore, the results show that the duration of the game increases linearly with improvements in handicap. ¹¹

Limitations of the Study

Despite the advantages of using HR as an indirect parameter in evaluating EE, conventional methods of estimating EE based on the level of human resources also have the following limitations:

• The assumption of steady-state conditions does not consider inconsistencies in the HR-AEE relationship (eg, when exercising intensity changes dynamically).

• Non-metabolic increases in HR affect outcomes (eg, physical, mental, and non-exercise-related stress).

• Changes in the body’s metabolism that occur during prolonged PA or recovery are not considered.

Concerning the first point, steady state can be achieved only with sustained and constant-load exercise, which is not the case with golf.

Practical Applications

The results of this study would be very useful for the training of professional and amateur golfers. It provides a pattern of the physical demands exerted in completing a round of golf and can lead to a more precise and accurate program prescription. Players should be more active in accessing sports scientists and conditioning coaches who specialize in golf training to develop golf-specific attributes. The data collected during this research will ensure that golf coaches and conditioning coaches have a better understanding of the load placed on golfers, especially during tournaments. Coaches can therefore better assist players with building their conditioning programs, practice regimens, and nutrition while playing golf.

Conclusion

A professional player’s golf round is moderate PA. The EE was 5.2 cal/min, which is a moderate energy consumption. Though most wrist-worn devices adequately measure HR in laboratory-based activities, as an indirect estimate derived from a mathematical equation, the estimation of AEE must always be critically evaluated.