The Effects of Swimming Training on Arterial Function, Strength and Cardiorespiratory Capacity in Elderly Women With Stage 2 Hypertension
Phase: NA
Conditions: Menopause, Hypertension
Sponsor: Pusan National University

Document Date: 03/25/2019 
 
The effects of swimming on elderly women with stage-2 hypertension : full study protocol 
and statistical analysis plan 
 
NCT#03546270 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Full study protocol 
 
Participants 
One hundred women (age, 67-85 y) with stage 2 hypertension (systolic/diastolic BP: 140-179 / 
90-119 mm Hg) were recruited from multiple general practice centers. All participants had 
experienced the absence of menstruation for at least 1 year. They were not obese (body mass 
index >30 kg/m2) or smokers, did not have psychiatric conditions as assessed by medical 
history, and were not taking medications or hormone therapy during the year before the study. In 
addition, all participants were sedentary (<1 h of regular exercise per week in the previous year). 
All the participants gave written informed consent before their inclusion in the study. All 
protocols were approved by the Public Institutional Review Board designated by the Ministry of 
Health and Welfare (P01-201511-11-001), carried out in accordance with the Declaration of 
Helsinki, and registered in clinicaltrial.gov (NCT03546270).  
 
Study design 
Allocation was stratified randomly, and sequence was generated by a computer-based number. 
After baseline measurements, participants were randomly assigned to 20 weeks of SWM training 
(n=52) or to a no-exercise control (CON, n=48) group. Laboratory personnel were not aware of 
the allocation. Measurements were obtained at baseline and at 20 weeks during the same time of 
the day (±1 hour), in the morning, after an overnight fast and after abstaining from caffeinated 
drinks and alcohol between 48 and 72 hours after the last exercise session. Cardiovascular 
measurements were collected in a quiet temperature-controlled room (22-24 ⁰C) after at least 10 
minutes of rest in the supine position. After resting vascular measurements, body composition, 
muscular strength and cardiorespiratory fitness were assessed. Participants were instructed not to 

alter their regular lifestyle habits during the study period (verified through food/physical activity 
logs). 
 
Swimming training program 
Participants performed SWM training (combination of free style, breast stroke, and backstroke) 
for 20 weeks with instructors. For the first 5 weeks, participants swam 25 to 30 minutes/day, 3 to 
4 days/week at a relatively low intensity of exercise [~60% of maximal heart rate (HR)]. As their 
overall level of fitness and exercise skill improved, the intensity and duration of exercise 
increased to 40 to 45 minutes/day, 3 to 4 days/week at a moderate intensity of 70% to 75% of the 
maximal HR. Target HR was adjusted based on the observation that maximal heart rate during 
SWM is approximately 12 beats/min lower than that during running.23  Each participant was 
instructed to swim continuously except during the time needed for checking target heart rate [by 
Polar heart rate monitor (Polar Electro, Lake Success, NY)].  The training protocol was adapted 
from prior literature on middle-age and older individuals.14 Participants in the non-exercising 
control group did not participate in a supervised exercise program, visited the laboratory at the 
same frequency as participants in the swimming intervention and underwent recreational 
activities such as board games during this time. They were also encouraged to maintain their 
regular level of physical activity for the duration of the study. 
 
Vascular function 
BP was measured using an automatic oscillometric device (HEM- 705CP; Omron Healthcare, 
Vernon Hill, IL). A commercially available applanation tonometer (SphygmoCor; AtCor 
Medical Ltd, Sydney, Australia) was used with analysis software (version 8.0, SphygmoCor 

Cardiovascular Management Suite, West Ryde, Australia) for the measurement of carotid-radial 
PWV [(crPWV), an indicator of brachial arterial stiffness] and pulse wave analysis components. 
Aortic pulse waveforms were derived using a validated generalized transfer function. The aortic 
wave is composed of a forward wave, caused by stroke volume ejection, and a reflected wave 
that returns to the aorta from peripheral sites.24 Augmentation pressure (AP) is the difference 
between the second and first systolic peaks. The AIx was defined as the AP expressed as a 
percentage of the aortic pulse pressure. AIx was normalized to a HR of 75 beats/min (AIx@75), 
because it is influenced by HR.25 Two measurements were collected at each time point and 
averaged as previously described.26,27 The validity and reproducibility of noninvasive 
applanation tonometry measures derived from a SphygmoCor device has been previously 
shown.28 The intraclass correlation coefficient for all measurements derived from tonometry, 
calculated on 2 separate days in a subsample, was ˃0.90.  
 
Body composition 
Height and weight were measured to the nearest 1.0 cm and 0.1 kg, respectively. Body fat (%) 
and lean body mass were determined in all participants by using a bioelectrical impedance meter 
(X-SCAN PLUS II; JAWON Medical, Seoul, Korea).29 Bioelectrical impedance measurements 
have been shown to be valid and reliable predictors of body composition.30  In our laboratory, the 
intraclass correlation coefficient for all measurements derived from bioelectrical impedance 
taken on 2 consecutive days in a subsample was ˃0.95. 
 
Muscle Strength  

To determine upper body muscular strength, maximal isometric handgrip strength of the 
dominant arm (with duplicate) was assessed unilaterally using a standard handgrip strength 
dynamometer (JAMAR, Patterson Medical/Sammons Preston, Bolingbrook, IL). The validity 
and reproducibility of handgrip strength dynamometry is well known.31  In our laboratory, 
measures of maximal isometric grip strength calculated on 2 separate days in a subsample had an 
intraclass correlation coefficient ˃0.98. 
 
Cardiorespiratory Fitness  
The Cornell modification of the Bruce treadmill protocol was used to determine the maximal 
oxygen consumption (VO2max) for the participants.32 The test was terminated when the 
participants were unable to continue exercise or the researchers could see adverse symptoms or 
changes in electrocardiogram or in BP. VO2max was defined as the highest 30 seconds value of 
O2 uptake.32 The Cornell modification of the Bruce treadmill protocol has been shown to be 
valid and reproducible.33 The intraclass correlation coefficient for VO2max determined with this 
protocol on 2 separate non-consecutive days in a subsample, was ˃0.98. 
 
Statistical analysis plan 
Data are expressed as mean ± standard deviation. All parameters were normally distributed as 
shown by the Shapiro-Wilk test. Differences at baseline between groups were evaluated using 
unpaired t tests. A two-way analysis of variance with repeated measures (group x time) was used 
to compare differences after SWM training within and between groups. All analyses were 
performed using SPSS 21.0 for Windows (IBM SPSS Analytics, Armonk, NY). Statistical 
significance was set at P<0.05. A power analysis calculation determined a minimum sample size 

of 52 (26 each group) would allow for the observation of a difference of 3% to 5% between the 
groups (SWM vs control) on PWV and AIx with a power of 90%.14,19  Because increases of 20% 
in PWV and 10% in AIx have been previously associated with respective increases of 1.3-fold 
and 31.8% in the risk for cardiovascular events,34,35 an improvement of 3-5% in PWV and AIx 
would be considered clinically important.