Whether we are recreational athletes, enthusiasts, or professionals, exercise intensity is linked to the development of our physical condition. That is, for each of these types of practitioners, there is a "target zone" of intensity below and above which significant improvements do not occur. If we exercise at too low an intensity, our body will not "feel the need" to adapt and develop response mechanisms to that intensity, and therefore, improvements will not occur or will take longer; On the other hand, if the sessions have intensity levels above the target zone (excessive), in addition to being more prone to injuries, the bioenergetic pathways engaged will not be the most suitable to achieve the predefined goals. Thus, it becomes crucial to know what the ideal effort intensity will be for each person/goal.
In the sports and competition context, this intensity varies according to the progress of the training cycle. In the field of general health improvement, the American College of Sports Medicine (ACSM) and the American Heart Association (AHA) recommend at least 30 minutes of moderate-intensity physical activity 5 days a week or 20 minutes of vigorous-intensity physical activity 3 days a week or a combination of the two (1). So, regardless of the goal and the level of each individual, the question arises: How can I control the intensity of my training?
Control of effort intensity
The speech test (ST) is a way to try to understand the intensity of effort based on the ability to maintain a conversation (2).
Table 1 – Effort intensity scales based on the ease/difficulty of speaking
This scale, although it can serve as a basis for getting a general idea of effort (2,3), leaves much to be desired when it comes to the rigorous control of effort.
2 - SUBJECTIVE PERCEPTION OF EFFORT (SPE)
The Subjective Perception of Effort Scale (SPES) or Borg Scale reflects the psychological perception that an individual has of the effort they exert, with the aim of measuring the degree of intensity and effort experienced in a given task (4). This is one of the most commonly used methods for assessing and controlling effort intensity.
Fig. 2 - Borg CR10 Scale (on the left) and Borg RPE Scale (on the right).
Of the two scales developed by Borg, the RPE is the most used; level 6 would correspond to 60 beats per minute of the heart, and 20 to 200 beats per minute.
According to ACSM (5) for clinically healthy individuals in the general population, during a health-oriented physical activity program aimed at improving cardiorespiratory fitness, the subjective perception of effort should vary between 12 and 17 values (Borg RPE) or 3 and 7 values (CR10 Scale).
3 – HEART RATE
With the advent of technology, the use of heart rate monitors has become widespread, devices that can measure the number of heart contractions per minute (beats per minute, bpm) with considerable ease and accuracy. Nowadays, HR is the most used method to control exercise intensity in the daily lives of practitioners.
Among various methods, controlling intensity through heart rate reserve (HRreserve) is the most rigorous and consensual. The concept of HRreserve results from the combination of maximum heart rate (HRmax) and resting heart rate (HRrest), more specifically it refers to the range of variation of HR between the minimum and maximum value (HRreserve = HRmax – HRrest). The introduction of HRrest in the calculation of exercise intensity allows for a more rigorous prescription, as it takes into account the minimum HR value, which is specific to each individual and is influenced by training.
Fig. 2 – Representative scheme of heart rate reserve (HRreserve)
According to ACSM (5) for moderate intensity, HR should be between 40 and 60% of HRreserve and for vigorous intensity between 60 and 90%.
Calculation of HRreserve through the percentage of HRrest:
- Subject M/F
- Age: 40 years
- HRrest: 60bpm
- Desired intensity: Moderate / vigorous
1st step: estimate (if the exhaustion test has not been done) HRmax (6)
HRmax = 208 - 0.7 x age
HRmax = 208 – 0.7 x 40
HRmax = 180bpm
2nd step: calculate the HR reserve
HRrest = HRmax – HRrest
HRrest = 180 – 60
HRrest = 120bpm
3rd step: Calculate HRreserve
HRreserve = % HRrest + HRrest
Moderate intensity (40 to 60% HRmax):
40% FCres = 120 x 0.40 = 48 bpm + 60 bpm = 108 bpm
60% FCres = 120 x 0.60 = 72 bpm + 60 bpm = 132 bpm
Vigorous intensity (60 to 90% FCmax)
60% FCres = 120 x 0.60 = 72 bpm + 60 bpm = 132 bpm
90% FCres = 120 x 0.90 = 108 bpm + 60 bpm = 168 bpm
Based on the percentage of FCres, the FCalvo for our subject exercising at a moderate intensity would be between 108 and 132 bpm; for a vigorous intensity, between 132 and 168 bpm.
Conclusion:
Whatever methodology suits you best, what matters is that you adopt one and start monitoring the intensity of your effort to ensure you are in the right zone and, therefore, on the right path to achieve your goals!
Table 2 – Equivalence of the intervals of various methodologies with the intensity of effort
Author:
- Raul Bartolomeu, PhD, PhD Sports Science.
References:
- Haskell WL, Lee IM, Pate RR, Powell KE, Blair SN, Franklin BA, et al. Physical activity and public health: updated recommendation for adults from the American College of Sports Medicine and the American Heart Association. Circulation. 2007 Aug 28;116(9):1081-93. PubMed PMID: 17671237. Epub 2007/08/03. Eng
- Woltmann ML, Foster C, Porcari JP, et al. Evidence that the talk test can be used to regulate exercise intensity. J Strength Cond Res. 2015;29(5):1248–54.
- Gillespie BD, McCormick JJ, Mermier CM, Gibson AL. Talk test as a practical method to estimate exercise intensity in highly trained competitive male cyclists. J Strength Cond Res. 2015;29(4):894–8
- Borg G. Borg's Perceived exertion and pain scales. Champaign, IL: Human Kinetics; 1998. viii, 104 p. p.
- American College of Sports Medicine (2016). ACSM's Guidelines for Exercise Testing and Prescription. 10th ed. Philadelphia: Lippincott Williams & Wilkins
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001 Jan;37(1):153-6. PubMed PMID: 11153730.