Table 4.

Amplitudes and duration of electrocardiographic waves and intervals before and after exercise

Electrocardiographic characteristics (mean ± SD)	Preexercise	Postexercise	P
Amplitudes of electrocardiographic waves (mm)
P wave amplitude	1.84±0.48	2.57±0.76	<0.001
Q amplitude	1.74±3.45	2.08±2.07	0.394
R amplitude	20.06±6.51	20.25±6.97	0.651
S amplitude	2.47±2.55	3.03±2.98	<0.001
T wave amplitude	2.8±1.30	4.06±1.51	0.001
Durations of waves and intervals (s)
PR interval	0.108±0.018	0.089±0.019	0.002
P wave duration	0.075±0.014	0.06±0.01	0.001
P wave time to peak	0.04±0.05	0.03±0.008	0.127
QRS duration	0.072±0.198	0.06±0.01	0.006
T wave duration	0.11±0.02	0.09±0.05	<0.001
T wave time to peak	0.06±0.01	0.04±0.02	<0.001
QT interval	0.30±0.4	0.23±0.03	<0.001
QoT interval	0.19±0.03	0.14±0.03	<0.001
JT interval	0.23±0.04	0.15±0.04	<0.001
J to peak T interval	0.17±0.36	0.11±0.32	<0.001
Peak T to end T interval (Tp-e)	0.06±0.01	0.04±0.02	<0.001
Tp-e/QT interval	0.20±0.06	0.20±0.10	0.724
Tp-e/QTc (B)	0.15±0.04	0.12±0.06	<0.001
Tp-e/QTc (Fridericia’s formula)	0.17±0.05	0.14±0.07	<0.001
Tp-e/QTc (Framingham’s formula)	0.16±0.04	0.14±0.07	<0.001
Tp-e/QTc (Hodges’s formula)	0.16±0.04	0.10±0.06	<0.001
Absolute shortening of QT interval with exercise	0.226±0.30
QT shortening as fraction	24.6%±12.1%

SD: Standard deviation, QoT: Q to onset of T wave, JT: J point to end of T wave, Tp-e: T peak-T end interval, QTc: Corrected B: Bazett’s formula, QT: Onset of Q wave to the end of T wave, QRS: QRS complex, PR: PR interval