Every Tuesday, this site takes a look at a training or technology concept that shapes how tennis is played. This week’s inspiration comes from the behind-the-scenes feed at the Mutua Madrid Open, where Jannik Sinner was shown performing a lengthy sequence of exercises using a small yellow weighted ball. By the end of the segment, I had reached an unavoidable conclusion. I am becoming obsessed with the small weighted yellow ball.
Regular readers know this site has a long history with medicine balls, weighted throws, and rotational training. I have previously written about overhead weighted-ball throws, medicine ball groundstrokes, and balance drills incorporating weighted balls. In other words, none of what Sinner was doing was new at all. However, what has emerged is the consistency of that specific tool. I am seeing the same compact yellow weighted therapy ball showing up again and again.
Today, I am recapping the first two moves that appeared in Sinner’s most recent sequence. The first movement shown was a series of overhead throws, similar to the exercise I previously highlighted when Alexander Zverev was using a weighted ball to build explosive upward force. In Sinner’s version, he is performing overhead throws to activate the shoulder. Tennis players do not literally throw balls overhead in matches, but serves and overheads rely on many of the same force-production patterns.
The second movement will be even more familiar to longtime readers of this site: weighted ball groundstrokes. This remains one of my favorite off-court tennis exercises because it directly mirrors rotational loading and force transfer used on both forehands and backhands. That move features coiling, planting, and rotating to throw the weighted ball as if striking a groundstroke. In this instance, Sinner was using a much smaller ball than the heavier medicine-ball versions used to develop rotational strength.
That smaller form factor is great for pre-match warmups. A compact weighted ball can be gripped more naturally and fits into tighter spaces. It allows for quicker transitions between movements and may better replicate the hand speed and compact mechanics of hitting groundstrokes. Traditional medicine balls still have their place, especially for raw power work, but the smaller, weighted ball seems particularly well-suited for match preparation.
It is also worth noting that the repeated choice of yellow in these smaller weighted balls is almost certainly not accidental. Tennis players spend their lives tracking bright yellow objects moving at speed. That color is deeply embedded in the sport’s visual language and likely offers practical benefits during training. A yellow ball is easier to pick up in peripheral vision, easier to follow through movement, and more natural to coordinate with than a darker or muted color. When drills involve rapid handoffs, throws, catches, or rotational movement, visibility matters. In that sense, the color choice is not merely aesthetic. It is another example of training tools designed to align with the sensory demands of the sport.
At some point, pattern recognition takes over. When multiple elite professionals keep reaching for the same simple tool, it is worth paying attention. Sinner was not the first player I had seen using these yellow balls, but his extended sequence finally pushed me to act.
I already owned a two-pound weighted ball, but it is a marbled pink color. Sinner’s session, combined with the growing number of professionals now using bright yellow weighted balls, tipped my purchase-decision scales. I have now invested in a pair of yellow weighted balls of my own.
In the interest of avoiding pure redundancy in my home gym, I opted for the five-pound variation. If I was going to acquire equipment that overlaps with something I already own, adding a different weight felt like the most rational justification. Whether that is disciplined decision-making or consumer self-deception is left as an exercise to the reader.
Yellow Weighted Exercise Ball (<- Sponsored Link)
There is a broader lesson here about training equipment. Sometimes the most effective tools are not complicated. They are portable, versatile, and endlessly reusable. A small weighted ball can be used for a wide variety of tennis functional training moves. It is a piece of equipment that has earned its place in my home gym.
Next Tuesday, I will continue through the Sinner’s sequence with drills that haven’t previously been covered on this site.
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