Abstract: - The backpack used commonly affects posture and physical performance, resulting in increased

oxygen uptake and energy expenditure. The purpose of this study is to confirm the effect of the chest loads on

the reaching time of the cardiopulmonary response. Seventeen healthy men participants were monitored for

cardiopulmonary function continuously during walking exercise with the Ramp protocol and recorded the time

taken to reach THR, VO2 peak, RR Difference, maximal METs, maximal FECO2, and minimum FEO2. During

the exercise test, subjects were instructed to carry a backpack loaded at no load, 5%, 10%, and 15% body

weight in random order. There was a significant difference in the time to reach the THR, the oxygen intake

peak time, the maximum metabolic equivalent time, the respiratory rate increase, the minimum oxygen amount,

Received: August 13, 2023. Revised: January 3, 2024. Accepted: February 8, 2024. Published: April 4, 2024.

To breathe, oxygen is inhaled and delivered into the

bloodstream, and carbon dioxide is expelled through

exhalation after the oxygen has been consumed by

the body’s energy metabolism, [1], [2]. During

resistive loaded breathing, an appropriate central

essential in many physically demanding

occupations, with first responders and military

As the popularity of adventure sports, recreational

activities, and mountaineering increases, the use of

backpack carrying has expanded, [7], [8]. Thus,

jackets or backpacks that cover the entire trunk from

front to back reduce pulmonary function greatly,

[15]. Restriction of the chest decreases the

satisfaction and quality of distinct respiratory

sensations, including difficulty inhalation and

uncomfortable shallow breathing, [16], [17].

Carrying a load close to the body, such as a

backpack, affects lung function by restricting the

movement of the chest wall during breathing, due to

the structural frame, harness type, and weight of the

[20], [21].

unloading and large loads of absolute figures of 15

kg, 30 kg, and 45 kg on cardiopulmonary abilities

were presented, [22], [23]. But if you look at most

of these prior studies, you can only mention the

effects of absolute numerical load on

cardiopulmonary functions, and you can't see the

effects of proportional load on relative load on

cardiopulmonary functions.

load by examining the time to reach the

cardiopulmonary function response.

2.1 Participants

Seventeen healthy males participated in this study.

This study was approved by the Sunmoon

University Institutional Bioethics Committee (SM-

2.2 Procedures

This study was completed with repeated

measurement within-subject studies. Subjects

underwent basic anthropometric measurements

(height, weight). Subjects wore the same training

were analyzed for each breath. The data averaged

over 30 seconds were measured and BP was

measured every 2 minutes. To analyze the

cardiopulmonary function reactions during the

exercise tests with four backpack loads conditions,

unweighted, 5%, 10%, and 15% of BW, the time to

reach THR, VO2 peak, RR Difference, maximal

METs, maximal FECO2, minimum FEO2 was

recorded.

23 ℃). We asked the participants to drink 150ml of

cool water during rest. The researchers continuously

checked the condition of the subjects (heart rate,

blood pressure, motor stress, and ECG) and

immediately stopped the experiment if abnormal

conditions were observed.

2.4 Statistical Analysis

Statistical analysis was calculated using SPSS

version 20.0 for Windows (SPSS INC, Chicago, IL).

unload and 10%, unload and 15% load, 5% and 15%

load each (p<.05). There was no between 5% and

10% load, 10% and 15% load each (p>.05). As a

result of the post-test, the time to reach VO2 peak

between unload and 5% load decreased the most

(Figure 3).

during activity [29]. In this study, it was observed

that as the load weight increased, the reaching time,

which indicates a change in cardiopulmonary

physiological response, became faster. Previous

studies have shown that the torque-generating

capacity of ankle plantar flexors and knee extensors

is reduced by dynamometers before and after load

carriage transporting [30].

carrying leads to a less economical gait pattern, but

minimum FEO2 became shorter as the load

increased.

increased ventilation during continuous movement

(45 minutes at 68% VO2 peak), [34]. In a previous

study examining peak performance and

cardiometabolic responses to vest-wearing load

carrying among U.S. Army soldiers, peak walking

speed gradually and significantly decreased as vest

load increased, increasing the physiological cost of

some studies, the increase in metabolic rate during

exercise with progressive loads (15 to 45 kg) did not

show a systematic linear proportion to the change in

backpack weight, [23]. These results indicate the

and there was no significant difference between the

loads. Exercise induces increased ventilation

through increases in respiratory rate and tidal

volume. An increase in tidal volume is achieved

VO2 peak: Oxygen consumption peak (time)

RR: Respiratory Rate

METs: Metabolic equivalents (time)

FECO2: Fractional concentration of carbon dioxide

in expired gas (maximal time)

FEO2: Fractional concentration of oxygen in

expired gas (minimal time)

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