Table 1.
Characteristics of the studies included.
| Study | Participants (Sample Size, Age (Year), and Gender) | HRV Protocol (Method, Respiration, Position, and Sampling Frequency) | HRV Measures | Secondary Outcomes | Analysis Length | Intervention (Type, Duration, and Sessions/Week) | Control Group |
|---|---|---|---|---|---|---|---|
| [3] | 90 (E: 26; R: 26; ER: 21; CG: 17) Age: 49−52 ± 6-8 (E: 52 ± 7; S: 52 ± 8; ES: 49 ± 6; CG: 52 ± 8) 100% women |
Polar RS810i belt Spontaneous Supine n. r. |
CI, HF, LF, LF/HF, RHR, and SDNN | Approx. 600 beats | Endurance, strength, and combined endurance and strength 21 weeks E and R: 2, ER: 4 sessions |
yes | |
| [55] | 93 (E: 23; R: 25; ER: 29; CG: 16) Age: 55.6 ± 7.4 100% men |
Polar RS810i belt Spontaneous Supine 1.000 Hz |
ln HF, ln LF, RHR, and α1 | VO2 max | 5 min | Endurance, strength, and combined endurance and strength 21 weeks E and R: 2, ER: 4 sessions |
yes |
| [56] | 44 (TG 22; CG 22) Age: 58.48 ± 0.53 (EG: 57.86 ± 0.64; CG: 59.10 ± 0.83) 100% women |
3-lead ECG n. r. n. r. 500 Hz |
CV, HF nu, LF nu, LF/HF, mRR, NN20, NN50, pNN20, pNN50, RHR, RMSSD, SDNN, SDSD, TP, and VLF | BF, BMI, BM, and VO2 max | 5 min | Coordinative (step aerobics) 10 weeks 3 sessions |
yes |
| [57] | 39 (TG: 19; CG: 20) Age: TG: 50 ± 4.5; CG: 58.45 ± 4.8 100% women |
Polar RS800 belt Spontaneous Supine n.r. |
DFA total, RRTri, SD1, SD2, SD1/SD2, TINN, α1, α2, and α1/α2 | 1000 consecutive beats | Multimodal (functional training and walking) 16 weeks 3 sessions |
yes | |
| [58] | 36 Age: 59 (range: 55–71) 19 women, 17 men |
3-lead ECG Spontaneous Sitting n.r. |
HF%, LF%, ln LF/HF, RHR, and TP | HRR, SBP at rest and during ergometer test | 512 consecutive beats | Endurance (walking, jogging, running, cycling, and stepping); crossover design: 10 weeks LI or HI + 10 weeks sedentary + 10 weeks HI or LI 10 weeks 3 sessions |
crossover design |
| [59] | 12 Age: 59 ± 5 5 women, 7 men |
ECG 15 breaths/min n.r. n.r. |
mRR, RHR, and RSA | BM, BMI, BR, DBP, SBP, VO2 max, and WR | 5 min | Endurance (treadmill, elliptical trainer, or bicycle) 24 weeks 4 sessions |
no |
| [60] | 44 Age: 47.3 ± 5.4 100% women |
Varia Cardio TF4, ECG belt n.r. Supine n.r. |
HF, HF%, LF, LF/HF, LF%, MSSD, RHR, TP, VLF, VLF%, VLF/HF, and VLF/LF | BM, BMI, and VO2 max | 5 min | Coordinative (aerobic dance or step-dance) 24 weeks 3 sessions |
no |
| [61] | 23 Age: 59 ± 6 100% women |
ECG 12 breaths/min Supine 1.000 Hz |
HF nu, LF nu, LF/HF, ln HF, ln LF, ln TP, RHR, and SampEn | BP | 5 min | Resistance 12 weeks 2 sessions |
no |
Abbreviations: BM, body mass; BMI, body mass index; BP, blood pressure; BR, baroreflex sensitivity; CG, control group; CI, complexity index; CV, coefficient of variation; DBP, diastolic blood pressure; DFA, detrended fluctuation analysis; E, endurance training group; ECG, electrocardiography; ER, endurance and resistance training group; HF (nu), power in high frequency range (in normalized units); HF%, relative power in high frequency range; HI, high intensity training; LF (nu), power in low frequency range (in normalized units); HRR, heart rate recovery; LF%, relative power in low frequency range; LI, low intensity training; ln, natural logarithm; mRR, mean RR interval; MSSD, mean squared successive differences; NN20, number of pairs of adjacent NN intervals differing by more than 20 ms in the entire recording; NN50, number of pairs of adjacent NN intervals differing by more than 50 ms in the entire recording; n.r., not reported; pNN20, NN20 count divided by the total number of all NN intervals; pNN50, NN50 count divided by the total number of all NN intervals; R, resistance training group; RHR, resting heart rate; RMSSD, square root of the mean of the sum of the squares of differences between adjacent NN intervals; RRTri, triangular index; RSA, respiratory sinus arrhythmia; SampEn, sample entropy; SBP, systolic blood pressure; SD1, standard deviation of instantaneous beat-to-beat variability extracted from Poincaré Plot; SD2, standard deviation of the long-term variability extracted from Poincaré Plot; SDNN, standard deviation of NN intervals; SDSD, standard deviation of standard deviation; TG, training group; TINN, triangular interpolation of RR intervals; TP, total power; VLF, power in very low frequency range; VLF%, power in very low frequency range; VO2 max, maximum oxygen consumption; VO2 peak, peak oxygen consumption; WR, waist-to hip-ratio; α1, short-term component of detrended fluctuation analysis; and α2, long-term component of detrended fluctuation analysis.