While I love all strength sports equally, there’s a lot of juicy research that’s directly related to powerlifting performance, quite a bit less research directly related to weightlifting performance, and even less research directly related to strongman performance (and virtually no research related to more niche strength sports, like the Highland Games or Basque stone lifting). In addition, the research that does exist for weightlifting is valuable, but probably wouldn’t make for a great Stronger By Science article. Most of the research related to weightlifting focuses on applications of weightlifting training for improving the performance of team sport athletes – very little research focuses on improving weightlifting performance for its own sake.
However, we certainly haven’t forgotten about the long-suffering weightlifters who read our articles, and this Research Spotlight may be pretty valuable if you struggle with split jerk performance. A recent study allowed me to develop a little tool that may help you diagnose the weak link in your split jerk.
In a study by Soriano and colleagues, researchers assessed 1RM split jerk, strict overhead press, and back squat strength in 33 competitive weightlifters (20 males and 13 females). Back squats were performed weightlifting-style: with a high bar position and ass-to-grass depth.
From there, the researchers assessed the independent relationships between overhead press strength and split jerk strength, and between squat strength and split jerk strength via linear regression. Furthermore, they assessed the relationship between split jerk strength and a combination of both squat and overhead press strength via multiple linear regression.
Unsurprisingly, they found that overhead press strength, squat strength, and a combination of squat and overhead press strength were all strongly predictive of split jerk performance (r > 0.9). You can see these associations in Figures 1-3. The researchers also provided regression equations for all of these linear relationships, which allowed me to develop a little tool to help you assess the weak link in your split jerk performance.
First, pull up this spreadsheet. Make a copy or download it. Don’t request editing access.
Then, fill in your 1RM strict overhead press, squat, and split jerk numbers in cells B1-3.
From there, the spreadsheet will take care of all of the necessary calculations. In cells B5-7, it will calculate a) your predicted split jerk 1RM based solely on overhead press performance, b) your predicted split jerk 1RM based solely on squat performance, and c) your predicted split jerk 1RM based on a combination of squat and overhead press performance.
Based on this data, cell B9 will tell you your likeliest weak link. If your actual split jerk 1RM is more than 15% lower than would be predicted based on your squat and overhead press strength, then the spreadsheet will identify some combination of speed, skill, and technique as the most likely factor limiting your split jerk performance. If your actual split jerk 1RM is within 15% of your predicted 1RM, the sheet will check whether lower body strength (squat 1RM) or upper body strength (overhead press 1RM) is most likely to be your limiting factor. If your predicted split jerk 1RM based on overhead press performance is higher than your predicted split jerk 1RM based on squat performance, the spreadsheet will identify squat strength as your most likely limiting factor. If your predicted split jerk 1RM based on overhead press performance is lower than your predicted split jerk 1RM based on squat performance, the spreadsheet will identify overhead press strength as your most likely limiting factor.
Furthermore, the spreadsheet will assign a confidence rating to its predictions. For example, if you “should” split jerk 120kg (based on your squat and overhead press strength), but your 1RM split jerk is only 90kg, the spreadsheet will identify speed/skill/technique as your current limiting factor, and it will rate that as a high-confidence prediction, because there’s a huge gap between your predicted performance and actual performance. However, if your 1RM split jerk is 105 kg, the spreadsheet will still identify speed/skill/technique as your most likely limiter, but it will be a lower-confidence prediction, since the gap between your actual performance and predicted performance is considerably smaller. Similarly, if your predicted split jerk 1RM based on squat strength is 40kg higher than your predicted split jerk 1RM based on overhead press strength, the spreadsheet would identify overhead press strength as your most likely limiter, and it would have high confidence in that prediction. However, if the gap between those two predicted 1RMs was only 5kg, the spreadsheet would be less confident in predicting that overhead press strength is limiting your split jerk performance.
To be clear, I don’t think this is a foolproof, 100% perfect tool for diagnosing weaknesses in the split jerk. However, if you’re struggling with your split jerk, this little tool may just help point you in the right direction.
Note: This article was published in partnership with MASS Research Review. Full versions of Research Spotlight breakdowns are originally published in MASS Research Review. Subscribe to MASS to get a monthly publication with breakdowns of recent exercise and nutrition studies.