Premature Birth Could Impact Physical Fitness Later In Life

Preterm young adults have weaker muscular fitness than their counterparts born at full-term, according to a recent study carried out by Finnish researchers. These young adults also perceive themselves as less fit than their counterparts.

The study, which assessed muscular, cardiorespiratory, and self-rated fitness in preterm born young adults, further suggests that young adults born prematurely perceive themselves as less fit to their peers. There was, however, no difference in cardiorespiratory fitness among the young adults.

Pregnancy usually lasts for 40 weeks, and births that occur before 37th week are considered premature. Babies born before 34 weeks of gestation are considered early preterm, and births between 34 to 36 weeks are considered late preterm. Premature birth gives the baby less time to develop in the womb, and preterm infants often suffer complicated medical problems.

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Previous research has established that premature births can have long-term cardiovascular problems and lower physical fitness. Such research is more focused on the smallest and the most immature of preemies. The current study is important, according to lead author Dr. Marjaana Tikanmaki, because it implies the health risk extends to all the preterm babies, even those who are born closer to the full term.

“The differences in muscular fitness of young adults born preterm were detected in our study across the full range of preterm birth, but not for cardiovascular fitness,” Tikanmaki said by email.

Tikanmaki added, “The test we used to measure cardiovascular fitness may not be sensitive enough to detect small differences between those born preterm and those born at term.”

To study the impact of premature birth on fitness later in life, the researchers studied 139 early preterm young adults, 247 late preterm babies, and 352 full-term individuals. The average age of participants was around 23 years.

The researchers devised two tests to evaluate muscular fitness. The first test comprised of 40 seconds modified push-ups, which measured short-term endurance capacity of the upper body and the ability to stabilize the trunk.

On average, full-term women and men recorded 10 and 14 push-ups, respectively. Preterm adults, on the other hand, typically did one less push-ups than their peers.

In the second test to assess muscular fitness, participants were made to squeeze a force-measuring device using their dominant hands to measure their grip strengths. In this test, early preterm individuals registered lower grip strengths than their full-term and late preterm peers.

Lower muscular fitness is associated with various health disadvantages including higher blood pressure, impaired glucose regulation, poorer bone health and female hair loss.

As a measure of cardiorespiratory fitness, researchers monitored the heart rate of the participants at the end of a four-minute step test. The average was 160 beats for women and 153 beats per minute for men. The difference in heart rate of the preterm and full-term adults was not significant.

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Participants were also asked to score their fitness on a scale of 1 (very poor) to 5 (very good). On average, men gave themselves a score of 2.6, whereas women gave themselves a score of 2.3.

The early preterm typically rated themselves about 0.2 points lower than full-term participants. The self-rated fitness scores were in line with results the researchers observed from other tests.

One limitation of the study is that the cardiorespiratory fitness test did not necessarily push the participants to the edge. A rigorous exercise that often takes longer and gradually increase in difficulty until participants can no longer continue would have been a better test of participants’ cardiorespiratory fitness.

“It’s also possible that these relatively young participants may have been too fit relative to older adults to detect large differences in their cardiovascular health,” Tikanmaki noted.

The cause of lower muscular fitness may be a consequence of lower physical activities among preterm born young individuals. Therefore, the study highly recommends physical activities, particularly the ones that improve muscle fitness from an early age such as shoulder workouts, yoga, swimming and sports.

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