Zack Wong was enjoying a winning basketball season at Lower Merion High School when the pandemic hit last year. When school abruptly shut down, he had no idea he’d be away from his teammates for the next eight months, cutting short both his junior and senior year seasons.

At the time, Wong hoped the hiatus would be short, so he wanted to stay in shape. Understanding the importance of conditioning, he joined his team for Zoom workouts and exercised alone in the park and his backyard whenever he could. But it wasn’t the same as playing in team practice and actual games.

“We missed out on summer league play,” recalled Wong, 18, from Wynnewood. “There wasn’t a lot we could do.”

Wong also took advantage of the time off to have hip surgery to repair an ongoing injury. When he and his teammates returned to practices and games in November, they all needed a little extra time to get back in shape. To get them caught up without risking injury, the coach reduced the amount of sprinting and worked on conditioning and skill training.

“I listened to my body, so there were times I had to push myself to not do too much, but to do enough to gain that strength back,” he said.

Wong’s basketball team was just one of many high school programs that ended suddenly.

“The pandemic stopped all of our sports dead in their tracks,” said Jason Luty, Rothman Orthopaedics athletic trainer at Lower Merion High School. “We were here one day and then we were not. We didn’t come back until July 1st of last year and that was in a very limited capacity.”

While summer is a common season for high school athletes to work on training and conditioning, many athletes cut back on those important skills over the last year as they were encouraged to socially distance and ultimately spent more time indoors for online education. That left them in weaker physical shape, raising the risk of safety concerns, including injuries, and even cardiac, pulmonary, and hydration issues.

“We have already seen a huge rise in injury from less activity,” said Naomi Brown, a sports medicine pediatrician at Children’s Hospital of Philadelphia. “It’s incredibly important for all of our young athletes to be gradually returning back rather than thinking they can go back to the full amount pre-pandemic.”

Brown has seen an increase in stress injuries, from stress fractures to excessive irritation and swelling. Shin splints, for example, are a prelude to a stress fracture of the shin. Of the 80 or 90 patients she saw each week pre-pandemic, she estimates about eight or nine had a bone stress injury. Now it’s about 15.

She urges young athletes to start back slowly, and increase their intensity gradually, about 10% each week. For someone who has been completely sedentary, start with 15 to 20 minutes of activity daily for the first week, and if you feel OK, increase that by 10% the next week. If you feel pain, back down.

“Pain and soreness are a good indicator that you are doing too much,” she said. “I expect athletes to be sore when they haven’t done anything, and that’s OK. But if the pain is lasting for more than an hour after activity or if they have pain the next day, they’ve overdone it.”

Brown urges coaches to start with a conditioning evaluation to understand the fitness level of team members who may come back at different levels. High school athletes, specifically, may be more prone to injury than college athletes.

“Young athletes are still growing and developing and collegiate athletes have already hit full-scale maturity,” said Brown. “If the adolescents haven’t been active in a year, not only have they grown — in some of these kids by four to six inches — but their muscles have gotten tighter and weaker. So if they are specializing in a sport, they are going to be overdoing those muscles even more so.”

Brown also suspects a correlation between injuries and people spending more time indoors. The lack of sunlight has led to a deficit in many of her patients’ Vitamin D levels, which can lead to softer bones and a possible bone stress injury. Vitamin D is important in regulating calcium and phosphate to keep bones, teeth, and muscles healthy, especially for kids who are still growing.

“People get Vitamin D stores with sun exposure,” she said. “My feeling is that last summer and fall there was a lot less sun exposure and outdoor time because kids were in school virtually.”

At Lower Merion, Luty’s training staff paid close attention to students who appeared to be in poorer condition and might have struggled with cardiac and pulmonary issues while trying to keep up with the demands of returning to athletics. Coaches cut back on their typical training level until the athletes were reconditioned. For students coming back in the July heat, they needed to also focus on hydration.

“If they were struggling, we would pull them out much faster than normal, cool them off, remove them from play and monitor them daily to be sure they were bouncing back OK,” Luty said.

Brown points to one positive outcome from time off of competitive sports — exploring other activities like running or biking that they normally wouldn’t have time to do.

“It would be wonderful to see more athletes not just playing, but working on their skills and drills and overall body conditioning,” she said. “I would love to see the athletes diversify more, running or cycling with family instead of specializing in one individual sport.”

For Wong, the pandemic helped foster an even stronger sense of community among his teammates. “We got robbed of not being able to finish our season, so let’s not take any moment for granted,” he said. “Every game during our season this year, we played like it could be our last.”