CARDIAC & PERFORMANCE TESTING

CARDIAC TESTING

Depending on your age and risk factors we may utilize some or all of the following tests.

Electrocardiogram (EKG)

An electrocardiogram (EKG, ECG) is the most common heart tracing done. Electrodes are placed on the chest wall and collect information about the electrical activity of the heart. Aside from the rate and rhythm of the heartbeat, the EKG can provide indirect evidence of blood flow within arteries to heart muscle and the thickness of heart muscle.

Calcium Scan (coronary artery calcium scoring)

A cardiac CT scan for coronary calcium is a non-invasive way of obtaining information about the presence, location and extent of calcified plaque in the coronary arteries—the vessels that supply oxygen-containing blood to the heart muscle. Calcified plaque results when there is a build-up of fat and other substances under the inner layer of the artery. This material can calcify which signals the presence of atherosclerosis, a disease of the vessel wall, also called coronary artery disease (CAD). People with this disease have an increased risk for heart attacks. In addition, over time, progression of plaque build up (CAD) can narrow the arteries or even close off blood flow to the heart. The result may be chest pain, sometimes called "angina," or a heart attack.

Because calcium is a marker of CAD, the amount of calcium detected on a cardiac CT scan is a helpful prognostic tool. The findings on cardiac CT are expressed as a calcium score. Another name for this test is coronary artery calcium scoring. The goal of cardiac CT scan for calcium scoring is to determine if CAD is present and to what extent, even if there are no symptoms. It is a screening study that may be recommended for patients with risk factors for CAD but no clinical symptoms.

The major risk factors for CAD are:

  • high blood cholesterol levels
  • family history of heart attacks
  • diabetes
  • high blood pressure
  • cigarette smoking
  • overweight or obese
  • physical inactivity

A positive test means that CAD is present, regardless of whether or not the patient is experiencing any symptoms. The amount of calcification—expressed as the calcium score—may help to predict the likelihood of a myocardial infarction (heart attack) in the coming years and helps us decide whether you may need to take preventive medicine or undertake other measures such as diet and exercise to lower the risk for heart attack.

Echocardiogram (Echo)

The heart is a two-stage electrical pump that circulates blood throughout the body. The anatomy includes four chambers and four valves. For the heart to function normally these structures need to be intact and the heart muscle needs to beat in a coordinated fashion, so that blood flows in and out of each chamber in the proper direction.

An echocardiogram is an ultrasound test that can evaluate the structures of the heart, as well as the direction of blood flow within it. Technicians specially trained in echocardiography produce the images and videos, often using a special probe or transducer that is placed in various places on the chest wall, to view the heart from different directions. Heart specialists are trained to evaluate these images. The echocardiogram is just one of the many tests that can be done to evaluate heart anatomy and function. The test usually takes up to an hour to do. A standard echo doesn't require any special preparations or followup.

PERFORMANCE TESTING

Depending on your goals and individual athletic activities, one or more Performance Tests will be appropriate for you to get the data you need to start reaching your maximal potential.

Lactate Threshold

The lactate threshold is a point during exhaustive, all-out exercise at which lactate builds up in the blood stream faster than the body can remove it. Anaerobic metabolism produces energy for short, high-intensity bursts of activity (lasting no more than a few minutes) before the lactate build-up reaches a threshold where it can no longer be absorbed and, therefore, accumulates. This point is known as the lactate threshold and is usually reached between 50 to 80% of an athlete's VO2 max.

During moderate exercise the lactate can be absorbed quickly, but with high-intensity exercise it is produced faster than the body can absorb it. This lactate threshold is marked by a slight drop in pH (from 7.4 to about 7.2) that is thought to and cause fatigue and reduce the power of muscle contractions. At this point the athlete is forced to back off or slow down. 

Presumably, having a higher lactate threshold means an athlete can continue at a high-intensity effort with a longer time to exhaustion. Because of this, many consider LT a great way to predict athletic performance in high-intensity endurance sports and therefore LT is also used by many athletes to determine training plans.

Lactate Threshold Training

Lactate threshold (LT) training is a popular method of improving high intensity endurance performance. While V02 Max may indicate an athlete's genetic potential and natural ability, their lactate threshold can be increased substantially with the right training program. Athletes often use their lactate threshold to determine how to train and what sort of a pace they can maintain during endurance sports. Because the lactate threshold can be increased greatly with training, many athletes and coaches have devised complicated training plans to increase this value.

Measuring Lactate Threshold

In the lab, lactate threshold tests are performed in a similar manner to VO2 Max testing and use either a treadmill or stationary bike. The exercise intensity is increased in periods of about 4-5 minutes and blood samples are taken with a finger stick at the end of each period. Along with blood lactate concentration, heart rate, power output and VO2 are often measured. This process continues until the blood lactate concentration increases significantly. This tends to be a fairly obvious spike in the data. Because lactate threshold occurs sooner than VO2 max is reached, it is often measured as a percentage of VO2 max. Athletes and coaches measure the power output (usually in watts/kg) at their lactate threshold in order to design training programs.

Lactate Threshold Values

        The average person reaches their LT at 60 percent of their VO2 max

        Recreational athletes reach their LT at 65-80 percent their VO2 max

        Elite endurance athletes reach their LT at 85-95 percent their VO2 max

How to Increase Lactate Threshold

Debate continues regarding the science of the lactate threshold, whether there is such a point, and the value of trying to measure it at all. The good news for athletes is that although these numbers may or may not be proven, it has been shown that with training athletes are able to tolerate higher intensity exercise for longer periods of time.

Two simple ways to help increase your LT include:

  • Proper Training

        LT training means increasing your exercise intensity so you train at or just above your LT heart rate. This training can be interval training or steady training.

    •    Interval LT Training

    •    Sample Plan: Twice a week perform three to five 10 minute high effort intervals at 95-105 percent of your LT heart rate with three minutes of rest between intervals.

    •    Continuous LT Training

    •    Sample Plan: Twice a week perform one 20-30 minute high intensity effort at 95-105 percent of your LT heart rate.

  • Proper Nutrition

        To boost your LT during training and racing, you need to make sure you can exercise at a high intensity without running our of glycogen stores. This requires careful nutritional meal planning both in the pre-exercise meal and post-exercise meal.

VO2 Max

VO2 Max Measures Aerobic Fitness and Maximal Oxygen Uptake. VO2 max, or maximal oxygen uptake, is one factor that can determine an athlete's capacity to perform sustained exercise and is linked to aerobic endurance. VO2 max refers to the maximum amount of oxygen that an individual can utilize during intense or maximal exercise. It is measured as "milliliters of oxygen used in one minute per kilogram of body weight.” This measurement is generally considered the best indicator of an athlete's cardiovascular fitness and aerobic endurance.

Theoretically, the more oxygen you can use during high-level exercise, the more ATP (energy) you can produce. This is often the case with elite endurance athletes who typically have very high VO2 max values.

V02 max should not be confused with the lactate threshold (LT) or anaerobic threshold (AT), which refers to the point during exhaustive, all-out exercise at which lactate builds up in the muscles during exercise. With proper training, athletes are often able to substantially increase their AT and exercise longer at a higher intensity.

How Is VO2 Max Measured?

Measuring VO2 max accurately requires an all-out effort (usually on a treadmill or bicycle) performed under a strict protocol in a sports performance lab. These protocols involve specific increases in the speed and intensity of the exercise and collection and measurement of the volume and oxygen concentration of inhaled and exhaled air. This determines how much oxygen the athlete is using.

An athlete's oxygen consumption rises in a linear relationship with exercise intensity -- up to a point. There is a specific point at which oxygen consumption plateaus even if the exercise intensity increases. This plateau marks the V02 max. It's a painful point in VO2 max testing where the athlete moves from aerobic metabolism to anaerobic metabolism. From here, it's not long before muscle fatigue forces the athlete to stop exercising.

The test usually takes between 10 and 15 minutes and requires an athlete to be completely rested and motivated to endure the pain long enough to find the true VO2 max. VO2 max also can be estimated. There are a variety of protocols used to estimate VO2 max, one is called the Bruce Treadmill Test, but none are as accurate as direct testing.

Can You Change Your VO2 Max?

Research shows that although VO2 max has a genetic component and it can also be increased through training. The two methods for increasing VO2 max include increases in both training volume and intensity. Research also indicates that the less fit an individual is, the more they can increase their VO2 max through training. In fact, novice exercisers have been able to increase VO2 max by 20 percent through proper training. Fit athletes have a harder time increasing their VO2 max, most likely because they are already so near their genetic potential.

Aside from genetic factors, three other components have a large influence on VO2 max namely Age, Gender and Altitude:

        Age - Although it varies greatly by individual and training programs, in general, VO2 max is the highest at age 20 and decreases nearly 30 percent by age 65.

        Gender - Many elite female athletes have higher VO2 max values than most men. But because of differences in body size and composition, blood volume and hemoglobin content, a woman's VO2 max is in general about 20 percent lower than a man's VO2 max.

        Altitude - Because there is less oxygen at higher altitude, an athlete will generally have 5 percent decrease in VO2 max results for every 5,000 feet they gain in altitude.

VO2 Max Highs and Lows

VO2 max results vary greatly. The average for a sedentary individual is close to 35 ml/kg/min. Elite endurance athletes often average 70 ml/kg/min.

One of the highest recorded VO2 max results (90 ml/kg/min) was that of a cross country skier. My 5 time Olympic Gold medalist partner Dr. Eric Heiden’s VO2 max was reported at 85 ml/kg/min when he was completely speed skating.

Does a High V02 Max Mean Better Athletic Performance?

Most elite athletes will have VO2 max values well over 60ml/kg/min, however, this number alone is not a guarantee of elite performance. A high VO2 max may indicate an athlete's potential for excellent aerobic endurance, but many other factors can determine the winner of a particular race. Some of these factors include: Skills Training, Psychological Preparation, Lactate Threshold Training, Rest and Recovery, Nutrition