# Heart Rate Variability in Basketball: The Golden Nugget of Holistic Adaptation?
## 2 HRV Measurement Protocols in Basketball  
Measurements of HRV in the basketball-related literature include short term measurements (ST, 5 min) [10; 36; 37; 38; 39; 40; 41], specific test and in-session measures [31; 32; 36; 42], sleep measures [43; 44], and ultra-short-term measures [30; 45]. [PERSON] et al. [37] measured the PSA of HRV through an electrocardiogram (ECG) for 5 min, analyzing the signal through an electrocardiogram connected to a PC (Personal Computer) at 100 s/s and analyzing the obtained data through specific software. In addition, [PERSON] et al. [38] analyzed the role of biofeedback in training through the measurement of HRV in a seated position, with the participants seated on a chair with their eyes closed, while [PERSON] et al. [39] measured ACB (Spain's First League) players over the same time duration but in a different body position; in this case, the participants were resting in a supine position for the measurement, a protocol that the same author later used for a posterior study with LEB Gold (Spain's Second Division) players [40]. [PERSON] et al. [46] used the same time frame (5 min) to measure the HRV of collegiate players, but in this case, the measurements were recorded during an incremental running protocol, as well as after the test. [PERSON] et al. [33] studied the HRV in a younger population (U-16), with a protocol of 5 min in a seated position before and after competition. The 5 min protocol can be placed within the short-term group of HRV measurements [6], which are the product of two processes: (a) mainly concerns the complex and dynamic relationship between the sympathetic and parasympathetic branches, while (b) relates to the regulatory mechanisms that control HR via respiratory sinus arrhythmia (RSA) and the baroreceptor reflex and rhythmic changes in the vascular tone [47]. Longer periods of recording provide information about cardiac variations in response to a wider variety of environmental and stress factors [6], such as training load variations produced by conditioning tests or training sessions.  
Longer durations of measurement were utilized by [PERSON] et al. [34] in a study where participants were assessed in an orthostatic position for 10 min, both before and after a vertical jump assessment. Similarly, [PERSON] et al. [35] employed the same duration to investigate the effects of sub-maximal tests and a Yo-Yo IR1 test on participants positioned in a resting posture, as outlined by the authors, to gather HR data. In another study focusing on workload effects, [PERSON] et al. [36] conducted an incremental test to volitional fatigue while simultaneously recording gas-exchange measurements and the HRV of the subjects during the tests. Additionally, [PERSON] et al. [9] utilized 10 min measurements in a seated position, before and after practice, to examine the impact of training sessions. [PERSON] et al. [42], [PERSON] et al. [32], and [PERSON] et al. [10] collected HRV measurements of amateur basketball players during training sessions and specific ball drills (5 vs. 5) to assess their response to training. Moreover, [PERSON] et al. [33] and [PERSON] at el. [44] analyzed HRV measurements obtained during sleep, using wearable devices to understand the variations influenced by factors affecting sleep quality. Regarding ultra-short-term measures, [PERSON] et al. [30] studied female under-18 and under-20 players before a European championship, using a 90 seconds morning measurement in a seated position.  
In conclusion, various protocols have been used in basketball studies, with different results found. Nevertheless, to ensure the validity and applicability of the results obtained when monitoring the heart rate responses within a group of athletes, consistency in measurement protocols is needed for the reliability and subsequent interpretation of the results obtained.