A young soccer player has a school match on Tuesday, a hard club practice on Wednesday and a private speed session on Thursday. Each coach has a good reason for what they’ve planned. The school coach wants to win the match. The club coach needs to work on pressing. The speed coach wants to teach the athlete how to brake and change direction.
Who’s looking at what those three days ask of the same kid?
That’s what I mean by load distribution. I want to know how much work an athlete is doing, what kind of work it is and where it sits in the week. Two players can train the same number of hours and have very different weeks. One plays ten minutes on Tuesday. The other plays the whole match and spends Wednesday chasing down opponents and cutting at speed. On paper, both attended the same sessions. As their strength and conditioning coach, I’d make different decisions for them on Thursday.
What got me thinking about ligaments
I was reading a review by Bleakley and Netterström-Wedin on how mechanical loading affects ligament healing. In the discussion, they pointed to a study by Paxton, Baar and colleagues that caught my attention. The researchers repeatedly stretched engineered ligament tissue in a lab. One cellular signal involved in the response to loading peaked at about 10 minutes. The tissue was temporarily less responsive to a second bout, and that particular signal responded fully again by about six hours.
Over seven days, the tissue exposed to short, spaced bouts had more collagen than the tissue exposed to continuous stretching.
The review itself focused on injured ligaments in animal models, and the authors identified methodological limitations that raised the risk of bias. There are two questions here. How confident can we be in the results of those experiments? And how well do they apply to a healthy, growing athlete? Even a well-designed animal study on ligament healing can only take us so far with that second question. Bleakley and Netterström-Wedin, 2023
The six hours describes when one cellular signal responded again in a lab. For me, the interesting question is what the spacing of hard efforts might mean in a real training week. If a kid already had two demanding days, what are we hoping to get from a third? I wonder if we are disrupting the healing and remodeling process and weakening the tissue over time? Yet, people are recommending the FIFA11+ still - as if that will solve the real problem.
A growing knee handles load differently
The ACL is a band of collagen fibres that connects the thigh bone to the shin bone and helps stabilize the knee. During growth, both the ligament and the bone it attaches to are developing. A small human lab study found that children’s ACL tissue stretched more before failure and tolerated less tension for its size than adult ACL tissue reported in other studies. That suggests mature tissue may be able to withstand more tension under lab conditions. How that translates to the chance of tearing an ACL during a game is a separate question.
In a younger child, a force through the ACL can sometimes pull off a small piece of bone where the ligament attaches to the shin. That’s called a tibial spine avulsion. Children can also tear the ligament itself. I find that example helpful for parents because it shows how development can change where an injury occurs. The ligament and its attachment have to handle the force together.
Now think about what else can change over a summer. A player comes back taller, heavier and faster. They’re carrying more momentum into the same cut they practised last season. Can they brake and redirect at that speed? Have they had a chance to practise it with fresh legs before they’re asked to do it late in a game against an opponent?
U.S. surveillance data show that reported ACL injury rates have risen in high school sports. We also know that many ACL injuries in high school soccer happen without contact. What I haven’t found is a study showing whether the rate of non-contact tears specifically has increased over ~20 years in 12- to 17-year-olds. My question as a coach is whether the way we stack games, practices and extra training contributes to some of these injuries. That’s a theory I’d like to see tested.
I wonder whether some young athletes face high-speed, high-force situations more often than they’ve had a chance to build the capacity to handle them. Then we put those exposures close together and give them very little room to recover. An ACL tear can happen on a single plant. I’m interested in the days and weeks leading up to that plant. Whether the spacing of those sessions changes injury risk is a question I’d like to see tested in young athletes.
What I do with this
If that soccer player comes in on Thursday after a full match and a club practice full of hard cuts, I can still give them a productive session. I might keep the strength work, adjust the volume and save the high-speed braking drills for another day. When there’s room in the week, I can teach braking in a planned drill, then increase the entry speed, change the angle or add a decision as the athlete gets better at handling it. I want them to build those skills because the game is going to ask for them.
I also want to know what the athlete actually did. How many minutes did they play? Was practice mostly technical work, or were they repeatedly sprinting and cutting? What’s coming up this weekend? And when I ask for a day off organized training, I mean a day that’s visible on everyone’s schedule.
Before I add another hard session, I want to know what the athlete has already done, what they need to get better at and when they’ll have the chance to do that work well. If three adults are writing three good plans for the same kid, someone still has to put those plans together.
