Symmetric vs Asymmetric Cores

Knowing whether you need a symmetrical ball or an asymmetrical ball for the next piece of your arsenal is more important than you may think. Understanding the difference between the two can be a daunting task even for the seasoned professional, but once you have familiarized yourself with the main factors engineered into the ball construction process the sport becomes much clearer and adjustments become easier. Please keep in mind, however, that the information which follows may lead you to your nearest bottle of aspirin! It can be quite technical in nature, so don’t be alarmed if you need to re-read this article a few times before it starts to make sense.

The term differential is the common nomenclature for the difference between the maximum and minimum RG values. The larger the number, the greater the flare potential becomes for the bowling ball.

The radius of gyration, or RG as commonly known, is a measurement in inches from the axis of rotation at which the total mass of a body might be concentrated without changing its moment of inertia. Low RG balls rev up faster and more easily, creating more ball motion, or change of direction.

Total differential (flare potential) can be described as the difference between the X (low RG) and Y (high RG) axes of any bowling ball, symmetrical or asymmetrical.

Intermediate differential is typically only expressed on asymmetrical balls and is the difference in the RG between Y (high RG) and Z (intermediate RG). Intermediate differentials exist on most symmetrical balls, but is not large enough to make a significant impact on the ball’s overall motion.

Differential ratios mandate how asymmetrical a ball is and can be found by dividing the intermediate differential by the total differential. Balls with a larger ratio have a higher degree of asymmetry. Symmetrical balls have the lowest differential ratios in the industry.

There's a Time and Place

A symmetrical core has an RG (radius of gyration) values of the Y (high RG) and Z (intermediate RG) axes of the ball do not differ by more than 5% of the total differential of the ball. An asymmetrical core is a ball where the RG values of the Y and Z axes of the ball differ by more than 5%. It’s generally accepted that symmetrical drilled balls have a smooth, controllable motion. Asymmetrical balls have a defined, angular shape downlane that respond to friction quicker than symmetrical balls, given the same coverstock composition and preparation. All balls, symmetrical or asymmetrical, become asymmetrical after drilling. Simply put, asymmetrical cores are not in equal proportion top to bottom like a symmetrical core is.

Asymmetrical balls can exhibit large amounts of track flare even with long pin-to-PAP (positive axis point) distances. A 6″ pin-to-PAP distance layout on a symmetrical ball will typically result in a very low-flaring ball. In a strong asymmetrical, however, a 6″ pin-to-PAP distance layout might result in a very high-flaring ball. This is the critical difference between symmetrical balls and asymmetrical balls. This leads to another interesting conclusion: asymmetrical balls can, in general, provide a ball driller with more reaction options than symmetrical balls. Symmetrical balls have only two ball motion "tuning parameters": pin-to-PAP distance and pin buffer. Asymmetrical balls add a third variable to the equation in the placement of the PSA (preferred spin axis) in relationship to the bowler’s PAP. The higher the undrilled intermediate differential is, the more significant the PSA position becomes.

Bowlers who favor the use of an asymmetric core need a little extra help curving the ball. These balls rev up fast and finish strong with a more aggressive movement downlane. Asymmetrical balls are great for heavy amounts of oil or longer patterns which don’t provide a lot of friction while symmetrical balls are typically smoother and yield a benchmark type of reaction that are more controllable. Symmetricals have two principal moments of inertia (X and Y axes) and asymmetricals have three (X, Y, and Z.) This greater degree of asymmetry is responsible for the highly dynamic moves asymmetrical balls can create.

And finally, don’t forget that there has to be a proper marriage between cover, core, and layout for the ball to react optimally, but we will save that for a later discussion.

 


Bowling for Health and Performance

There is an overlap between games and sports. Generally, sports require some sort of physical effort of specialized skill while games are more organized affairs with rules. The word game has several meanings. You can, for example, play a game of sports, but you can't sport a game. A good example would be if you think of the Olympics. The Olympics are referred to as the Olympic Games yet the game is a competition to collect as many medals as possible by partaking in specific sports. Whether you are a fulltime professional or a weekly leaguer, there’s no refuting that bowling deserves its place on the pillar amongst other sports. A physiological analysis confirms bowling requires strength, cardiovascular endurance, and flexibility to perform in the upper echelons of the competitive scene. Long gone are the days of calling bowling a “pastime.” Cutting-edge knowledge and techniques are being applied to the training protocols of top professionals and Team USA members. Being cognizant of your personal fitness levels can only help propel you to the top of your game as well.

Physical activity alone promotes muscle toning and strengthening, weight loss, stress relief, and reduced risk of disease. Depending on your weight, you can burn 200-600 calories per hour of bowling. Not only does bowling favor the aforementioned benefits, it can improve your social life, increase hand-eye coordination, and can be enjoyed at any age. Unlike most sports, the health gains far outweigh the risks for injury. Incorporating strength training, cardio, and stretching into your daily routine will not only make you a better bowler, it will improve your overall quality of life.

It’s been noted that Alzheimer’s patients can benefit from bowling because it improves balance and preserves motor skills. Also, repetitive movements like that of bowling may decrease anxiety because patients don’t have to make decisions about the activity.

Warm-ups and flexibility have been traditionally linked, but it is important to differentiate between them as they have different key functions. Warm-up is designed to prepare an athlete for training or competition and can improve subsequent performance and lessen the risk of injury. A well-designed warm-up can increase muscle temperature, core temperature, and blood flow and also disrupt transient connective tissue bonds. These effects can have the following positive impacts on performance:

  • Faster muscle contraction and relaxation of both agonist and antagonist muscles
  • Improvements in the rate of force development and reaction time
  • Improvements in muscle strength and power
  • Lowered viscous resistance in muscles
  • Increased blood flow to active muscles
  • Enhanced metabolic reactions

The degree of movement that occurs at a joint is called the range of motion (ROM). The ROM of a particular joint is determined by a number of factors including connective tissue structure, activity level, age, and gender. Range of motion is specific to each joint’s anatomy and the movements required at that joint. Flexibility is a measure of ROM and has static and dynamic components. Static flexibility is the range of possible movement about a joint and its surrounding muscles during a passive movement. Static flexibility requires no voluntary muscle activity; an external force such as gravity, a partner, or a machine provides the force for a stretch. Dynamic flexibility refers to the available ROM during active movements and therefore requires voluntary muscular actions. Stretching should be performed following practice and competition. Post practice stretching facilitates ROM improvements because of increased muscle temperature. It should be performed 5 to 10 minutes after practice. The increased body temperature increases the elastic properties of collagen within muscles and tendons, which allows for a greater stretch magnitude. Post-practice stretching may also decrease muscle soreness. If increased levels of flexibility are required, additional stretching sessions may be needed. In this case, stretching should be preceded by a thorough warm-up to allow for the increase in muscle temperature necessary for effective stretching. This type of stretching can be especially useful as a recovery session on the day after a tournament or league play.

Bowling is primarily considered an anaerobic sport, or one that does not place a demand on the cardiovascular system such as running or swimming. It focuses on short bursts of anaerobic power that stress the musculoskeletal system instead of the circulatory and pulmonary systems. During activity, the degree to which aerobic and anaerobic systems contribute to the energy being produced is determined primarily by the intensity and secondarily by the duration. Because a bowling session can last a few hours over the course of several days in most tournaments, training the cardiovascular system is equally as important as training for strength and power.

Because bowling is predominantly an anaerobic activity where you don't get sweaty and winded, it may not look, or even feel, like you're exercising.

Bowling competitively requires a certain amount of physical prowess from head to toe. Strength training the upper body, core, and lower body is more important now than ever before. Exercises for your upper body you can do at home like push-ups, bicep curls, and dumbbell rows can go a long way for your game. Grip strength is a commonly forgotten area of great importance. Even squeezing a racquetball at your office desk as little as 10 minutes a day can help make that 15lb ball feel several pounds lighter over time. Lunges, squats, and calf raises are excellent strength building exercises for your lower body, but developing your stabilizer muscles via balance and isometric exercises can be a game changer.

Prime movers work more efficiently with strong stabilizer, or fixator, muscles. Stabilizers contract, primarily isometrically, to immobilize a limb so that another part of the body can act. For example, the hip flexors are immobilized during knee flexion, and the abdominal muscles serve as stabilizers when the arms rolls a ball. In bowling, when the core muscles act as stabilizers the trunk transmits leg power to the arms, which translates to ball speed. A weak stabilizer inhibits the contraction capacity of the prime movers. Improperly developed stabilizers may hamper the activity of major muscles. The arms and legs are only as strong as the trunk. A poorly developed core is a weak support for hard-working limbs. Strength training programs should first strengthen the core muscle before focusing on the arms and legs.