How is the calf injury affecting Bengals QB Joe Burrow?

CINCINNATI -- For more than two months, Cincinnati Bengals quarterback Joe Burrow has had to answer questions about the health of his right calf.

After he strained the lower leg muscle on July 27, he didn't practice for more than a month as he followed a rehab plan to get ready for the regular season. Once back, he aggravated the calf injury in a Week 2 loss to the Baltimore Ravens.

When Burrow was healthy, Cincinnati was the betting favorite to win its third straight AFC North title and was in the mix of Super Bowl contenders. But since Burrow's calf injury, Cincinnati's offense has been one of the worst in the NFL, scoring three touchdowns in four games, which is the lowest total in the NFL heading into Week 5.

Burrow's numbers have been the most surprising. He entered the season with the highest completion percentage for a career in NFL history (68.2%). Since Burrow entered the league in 2020, the former No. 1 overall pick also had the lowest percentage of off-target throws (12.2%), according to ESPN Stats & Information. This year, he has the third-worst completion percentage (57.6%) and ranks 23rd in off-target throws (17.4%). Burrow is also the first quarterback in NFL history to attempt at least 150 passes in his team's first four games and fail to average at least five yards per attempt, per ESPN Stats & Information.

Following the team's 27-3 loss to the Tennessee Titans in Week 4, Bengals coach Zac Taylor acknowledged the injury is affecting Burrow.

"He's doing everything he can," Taylor said. "He's playing through it, but there's still limitations he's got, certainly, and that's probably very difficult for him."

Here's how the calf injury is impacting Burrow and the Bengals as they try to get back on track against the Arizona Cardinals on Sunday (4:05 p.m. ET, Fox).

How are throwing mechanics affected by an injured calf?

The right leg is the one that Burrow plants and pivots on when he throws. When he came back from the torn ligaments in his left knee that he suffered in 2020, he worked on adding power to his throws with throwing coach Jordan Palmer the following offseason in addition to the rehab process for that injury.

After Burrow initially suffered the strained calf in July, he said that he took time off from throwing in order to protect his mechanics. Since returning from the injury, he has admitted to tweaking his mechanics to compensate.

"It's something I've had to think about," Burrow said on Sept. 27. "[I'm] trying to find ways to get velocity on it, maybe without putting as much pressure on that calf. As it gets healthier, I'll be able to kind of change that."

Any athlete who throws an object for a living generates power from the ground, which moves through the legs and core before going up to the arm and the release point.

How Burrow manages to generate power in the wake of the calf injury is important. Adjusting his throwing motion and generating power or range of motion from other regions of the body could increase strain and result in a compensatory injury elsewhere.

After the Week 4 loss to Tennessee, Burrow said generating power on throws hasn't been the main issue. Instead, he said, what has yet to return is the quick-twitch movements that allow him to move around in -- and escape -- the pocket quickly.

"There's not too much quick twitch involved in the calf [in] the throwing movement," Burrow said, "just certain pocket movements mainly. I haven't gotten out and run or anything."

How important is resting the calf to aid healing?

Throughout the regular season, Burrow has been clear that rest alone isn't going to heal his calf.

"It'll get better each week I don't have a setback," Burrow said on Sept. 27 after the Week 3 win against the Los Angeles Rams. "So it was big to get through Monday without having any setbacks. That means it will be stronger this week. And if I get through this week without having any setbacks, it'll be stronger the next week."

While rest does play a key role, especially in the early phase post-injury or post-setback, acclimating the calf to the demands of his sport while progressively increasing his strength, endurance, power and workload tolerance remains important, even as he continues to play. And the situation Burrow is currently dealing with is different from when he was initially injured in training camp.

Before the season, Burrow and the Bengals staff said he was following a structured rehab plan with a goal of Burrow being ready for Week 1, which was a little more than six weeks from the day he initially suffered the injury. The hope was that the combination of rest (Burrow did not play at all in the preseason and returned to practice on Aug. 30) and rehabilitation before returning to action would mitigate the risk of recurrence.

All soft tissue injuries come with a risk of reinjury when an athlete returns to action, however. Recurrent injury following a calf strain in high-performance athletes ranges from 19% to 31%, according to a 2022 article in JBJS Reviews. But now, Burrow is simultaneously trying to manage his calf recovery while also playing in games.

"You just adapt to what you're dealing with, adapt to how you need to play and you take that week-to-week, day-to-day," Burrow said Wednesday.

Is Burrow at risk for a more serious injury if he continues playing?

There are examples of quarterbacks who have suffered calf strains in-season and returned to play without any major issues. In 2021, former San Francisco 49ers quarterback Jimmy Garoppolo suffered a right calf injury in Week 4 against the Seattle Seahawks and was forced to exit the game. He missed Week 5 as a result and returned to action in Week 7, following the team's bye. He played all remaining games, except Week 17, and then returned to play from Week 18 through the NFC Championship Game.

The same year, Dallas Cowboys quarterback Dak Prescott, who had missed the final 11 games of the previous season due to an ankle fracture, suffered a calf strain in Week 6. He rested during the ensuing bye week, missed the Week 8 game and came back for a contest against the Minnesota Vikings. While he admitted it wasn't his best season, he played in every game the rest of the year. He didn't blame his performance on the calf.

"I went through a period in the time right there in the season and just didn't play my best ball, and people tried to say it was the calf," Prescott told "The Rich Eisen Show" in February 2022. "The calf got better. I did everything that I needed to do for it to heal."

There are also less favorable examples.

Former Colts quarterback Andrew Luck suffered a calf strain in the spring of 2019, but the injury persisted into training camp. Luck retired before the season began. At the time, he hinted it was the cumulative toll of football that led to the decision, rather than the calf injury in isolation..

New York Jets quarterback Aaron Rodgers, who is giving Burrow advice on how to deal with the injury, is one of the rare quarterbacks who suffered a torn Achilles after previously having calf strains (including one sustained during conditioning drills with the Jets in May OTAs). But it's unfair to speculate whether Burrow could be at a similar risk.

There's no way of knowing whether Rodgers' prior calf strains played a role in his latest injury given that multiple variables can contribute to Achilles tendon failure. From a mechanical standpoint, during the play in which Rodgers was injured, his tendon was already under extreme tensile stress (extreme stretching/elongation of tendon) when his foot was planted pre-push-off while running. The defender falling on him as he was pushing off that leg added additional load, making him vulnerable to an Achilles rupture in that moment.

The majority of acute Achilles tendon ruptures occur during an explosive movement that places high load on the tissue. While other variables such as age, gender, tendon health, prior injury, training techniques and footwear may contribute as risk factors, there is no established scientific data that definitively determines whether or not a calf strain portends a future Achilles tear.

Burrow and those around him are hopeful that the longer he goes without any setbacks, the more he will be able to continue his recovery and move closer to full strength. One of the challenges with this type of injury is that despite the existence of metrics that can show progress in various areas (e.g. strength/power/endurance/acceleration), there is no single definitive test or measurement that can ensure there is no risk of recurrence with activity.

Perhaps equally important to restoring preinjury performance, yet more difficult to measure, is confidence. Return from a calf strain, particularly after a setback, can impact an athlete's confidence that the muscle will respond as it should on demand, without failing.

"The hope is that he's getting better every time he steps out there and feels more confident as he plays," said Bengals offensive coordinator Brian Callahan. "I think that that's where his mindset is too. He feels better and plays better and starts to get a little momentum back from dealing with it for as long as we have."