"Carbohydrate ... during exercise of about 45 minutes or longer can improve endurance capacity and performance." That's what the authors of Sport Nutrition explain in this excerpt reprinted here with permission of the publisher, Human Kinetics.

"Convincing evidence from numerous studies indicates that carbohydrate feeding during exercise of about 45 minutes or longer (Jeukendrup 2004, 2008; Jeukendrup et al. 1997) can improve endurance capacity and performance. Studies have also addressed questions of which carbohydrates are most effective, what feeding schedule is the most effective, and what amount of carbohydrate to consume is optimal. Other studies have looked at factors that could possibly influence the oxidation of ingested carbohydrate, such as muscle glycogen levels, diet, and exercise intensity. Mechanisms by which carbohydrate feeding during exercise may improve endurance performance include the following.
* Maintaining blood glucose and high levels of carbohydrate oxidation. Coyle et al. (1986) demonstrated that carbohydrate feeding during exercise at 70% of V.O2max prevents the drop in blood glucose that was observed when water (placebo) was ingested. In the placebo trials, the glucose concentration started to drop after 1 hour of exercise and reached extremely low concentrations (2.5 mmol/L) at exhaustion after 3 hours. With carbohydrate feeding, glucose concentrations were maintained above 3 mmol/L, and subjects continued to exercise for 4 hours at the same intensity. Total-carbohydrate oxidation rates followed a similar pattern. A drop in carbohydrate oxidation occurred after about 1.5 hours of exercise with placebo, and high rates of carbohydrate oxidation were maintained with carbohydrate feeding. When subjects ingested only water and exercised to exhaustion, they were able to continue again when glucose was ingested or infused intravenously. These studies showed the importance of plasma glucose as a substrate during exercise.
* Glycogen sparing in the liver and possibly muscle. Carbohydrate feedings during exercise “spare” liver glycogen (Jeukendrup et al. 1999), and Tsintzas and Williams (Tsintzas et al. 1998) discussed a potential muscle glycogen sparing effect. Generally, muscle glycogen sparing is not found during cycling (Jeukendrup et al. 1999), but it may be important during running (Tsintzas et al. 1995).
* Promoting glycogen synthesis during exercise. After intermittent exercise, muscle glycogen concentrations were higher when carbohydrate was ingested than when water was ingested (Yaspelkis et al. 1993). This finding could indicate reduced muscle glycogen breakdown. But the ingested carbohydrate was possibly used to synthesize muscle glycogen during the low-intensity exercise periods (Keizer et al. 1987a).
* Affecting motor skills. Few studies have attempted to study the effect of carbohydrate drinks on motor skills. One such study investigated 13 trained tennis players and observed that when players ingested carbohydrate during a 2-hour training session (Vergauwen et al. 1998), stroke quality improved during the final stages of prolonged play. This effect was most noticeable when the situations required fast running speed, rapid movement, and explosiveness.
* Affecting the central nervous system. Carbohydrate may also have central nervous system effects. Although direct evidence for such an effect is lacking, the brain can sense changes in the composition of the mouth and stomach contents. Evidence, for instance, suggests that taste influences mood and may influence perception of effort. An interesting observation provides support for a central nervous system effect. When a hypoglycemic person bites a candy bar, that person’s symptoms almost immediately decrease, and the person feels better again long before the carbohydrate reaches the systemic circulation and the brain. The central nervous system effect may also explain why some studies report positive effects of carbohydrate during exercise on performance lasting approximately 1 hour (Jeukendrup et al. 1997). During exercise of such short duration, only a small amount of the carbohydrate becomes available as a substrate. Most of the ingested carbohydrate is still in the stomach or intestine. Studies in which athletes rinsed their mouths with carbohydrate (but did not ingest any) during 1-hour time trials showed performance improvements similar to those that occurred when the athletes ingested the carbohydrate (Carter et al. 2004). Others (Pottier et al. 2008) recently confirmed these findings.

Whether the central nervous system effects of glucose feeding are mediated by sensory detection of glucose or perception of sweetness is not known, although studies with placebo solutions with identical taste to glucose solutions suggest that sweetness is not the key factor. Brain imaging studies also show that increased brain activity is specific to carbohydrates. Feeding Strategies and Exogenous Carbohydrate Oxidation

A greater contribution of exogenous (external) fuel sources (carbohydrate) spares endogenous (internal) sources, and the notion that a greater contribution from exogenous sources increases endurance capacity is enticing. The contribution of exogenous substrates can be measured using stable (or radioactive) isotopic tracers. The principle of this technique is simple: The ingested substrate (e.g., glucose) is labeled, and the label can be measured in expired gas after the substrate has been oxidized. The more the ingested substrate has been oxidized, the more of the label (tracer) will be recovered in the expired gas. Knowing the amount of tracer ingested, the amount of tracer in the expired gas, and the total CO2 production enables us to calculate exogenous substrate oxidation rates.

The typical pattern of exogenous glucose oxidation rates is shown in figure 6.6. The labeled CO2 starts to appear 5 minutes after ingestion of the labeled carbohydrate. During the first 75 to 90 minutes of exercise, exogenous carbohydrate oxidation continues to rise as more and more carbohydrate is emptied from the stomach and absorbed in the intestine. After 75 to 90 minutes a leveling off occurs, and the exogenous carbohydrate oxidation rate reaches its maximum value and does not increase further. Several factors have been suggested to influence exogenous carbohydrate oxidation including feeding schedule, type and amount of carbohydrate ingested, and exercise intensity."

Many of us know what water running is because we've been injured and wanted to keep the cardio up or as a preventative measure to reduce the bodily stress of pounding pavement. Here's an excerpt from Running Anatomy. It's published with permission of Human Kinetics.

"Most runners have been introduced to water running as a rehabilitative tool for maintaining cardiorespiratory fitness after incurring an injury that precludes dryland running. However, runners should not assume that aquatic training’s only benefit is injury rehabilitation. Running in water, specifically deep-water running (DWR), is a great tool for preventing overuse injuries associated with a heavy volume of aerobic running training. Also, because of the drag associated with running in water, an element of resistance training is associated with water running that does not exist in traditional running-based training.

Although shallow-water running is a viable alternative to DWR, its benefits tend to be related to form and power. Although the improvement of form and power is important, it comes at a cost. Because shallow-water running requires impact with the bottom of a pool, it has an impact component (although the force is mitigated by the density of the water). For a runner rehabbing a lower leg injury, shallow-water running could pose a risk of injury. More important, balance and form are easier to attain in shallow-water running because of a true foot plant. Fewer core muscles are engaged to center the body, as in DWR, and there is a resting period during contact that does not exist in DWR. For our purposes, all water-related training exercises focus on DWR.

In performing a DWR workout, proper body positioning is important. The depth of the water should be sufficient to cover the entire body: Only the tops of the shoulders, the neck, and the head should be above the surface of the water. The feet should not touch the bottom of the pool. Runners tend to have more lean body mass than swimmers, making them less buoyant; therefore, a flotation device will be necessary. If a flotation device is not worn, body position can become compromised and an undue emphasis is placed on the muscles of the upper body and arms to keep the body afloat.

Once buoyed in the water, assume a body position similar to dryland running. Specifically, the head is centered, there is a slight lean forward at the waist, and the chest is “proud,” or expanded, with the shoulders pulled back, not rotated forward. Elbows are bent at 90 degrees, and movement of the arms is driven by the shoulders. The wrists are held in a neutral position, and the hands, although not clenched, are more closed than on dry land in order to push through the resistance of the water. The strength gained from performing wrist curls and reverse wrist curls are beneficial for this.

Leg action is more akin to faster-paced running than general aerobic running because of the propulsive force needed for overcoming the resistance caused by the density of the water. The knee should be driven upward to an approximate 75-degree angle at the hip. The leg is then driven down to almost full extension (avoiding hyperextension) before being pulled upward directly under the buttocks before the process is repeated with the other leg.

During the gait cycle, the feet change position from no flexion (imagine standing on a flat surface) when the knee is driving upward to approximately 65 degrees of plantarflexion (toes down) at full extension. This foot movement against resistance both facilitates the mechanics of running form and promotes joint stability and muscle strength as a result of overcoming the resistance caused by drag.

Due to the unnatural training environment (water) and the resistance created when driving the arms and legs, improper form is common when beginning a DWR training program. Specifically, it is common to make a punting-like motion with the forward leg instead of snapping it down. This error is due to fatigue of the hamstrings from the water resistance, resulting in poor mechanics. To correct this error, rest at the onset of the fatigue, and don’t perform another repetition until the time goal is met. Do not try to push through it. You won’t gain fitness, and you will gain poor form.

DWR is effective because it elevates the heart rate, similar to dryland running. And because of the physics of drag, it requires more muscular involvement, thus strengthening more muscles than dryland running does without the corresponding overuse injuries associated with such training. Specifically, it eliminates the thousands of impact-producing foot strikes incurred during non-DWR running."

Here's a terrific excerpt from "Swimming Anatomy" published with permission of Human Kinetics.

"To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.

The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.

The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.

The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.

The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position."

I dream of gadgets that keep track of training I used to log. Then upload it to my computer and it does all the analysis and planning for me. I shoot out of bed awakening from the deep dream state, shaking my head of the fog...reality begins to set in as I look at the log book.

Here's a not-so-dramatic excerpt from The Runner's Edge, regarding runner's gadgets and is with the permission of Human Kinetics.

'The stop watch may become the "8-track" of the running world, but that doesn't mean runners need to be tech geeks to keep up. Stephen McGregor, PhD, lead author of The Runner's Edge (Human Kinetics, 2010), claims that by using speed and distance devices, runners of all levels can maximize performance.

"If you can work a stopwatch, you can learn how to manage your performance effectively with a speed and distance device," says McGregor. "And don't worry: This process will not strip running of its charming simplicity."

A speed and distance device measures elapsed time, distance covered, speed/pace, and elevation change. Many devices also have the capability to estimate calories burned and monitor heart rate-and some even track changes in VO2max.

McGregor claims that the real benefit to speed and distance devices, however, does not show up on the device, but on a runner's computer. "The power of the devices really begins with downloading workout data from the device to the computer," he explains. "Performance management software allows you to determine appropriate pace targets for all of your workouts and refine those targets as your fitness changes."

McGregor gives advice to people who are interested in purchasing a speed and distance device. He and coauthor Matt Fitzgerald analyzed the five basic brands on the market.

Garmin -- The manufacturer of GPS devices includes the GPS inside the wrist display unit. The authors give Garmin's Forerunner line high marks for accuracy, reliability and ease of use. Some Garmin speed and distance devices can be mounted on a bike handlebar and used as a cycling computer.

Nike -- The Nike+, developed with the Apple computer company, sold nearly half a million units in its first three months on the market in 2006, and almost all Nike running shoes are Nike+ compatible. The authors, however, warn that the Nike+ is not suitable for more serious performance management because it becomes increasingly inaccurate as the runner's speed varies from the pace run during initial calibration. "We recommend that Nike fans wanting to commit to digital performance management purchase the Triax Elite," says McGregor.

Polar -- Runners who place great importance on measuring heart rate while running should consider Polar, according to the authors. Polar integrates a heart-rate monitor with each of its speed and distance devices and McGregor and Fitzgerald believe they are the best heart-rate monitors on the market. One of Polar's speed and distance devices has options that allow it to function as a bike computer and power meter. The authors also commend Polar's performance management application, Polar Personal Trainer, hosted online at www.polarpersonaltrainer.com.

Suunto -- A latecomer to the speed and distance device market, experts widely agree that Suunto running products are as high quality as any. One of Suunto's unique advanced features estimates excess post-exercise oxygen consumption (EPOC) and use these data to calculate the training effect of each workout.

Timex -- The display watch aspect of Timex's speed distance devices makes them a good choice for runners who place a high value on the wrist display quality. "They are light and stylish enough to be worn all day, they have the 'takes a lickin' and keeps on tickin' factor,' and they have a better variety of information display options than other devices," says McGregor. "You can even configure your own custom display so that the watch shows the information you want to see where you want to see it."

Each model comes with performance management software, but McGregor also highlights Training Peaks WKO+, which works with all speed and distance devices. Training Peaks has cooperative relationships with most of the device manufacturers, who readily admit that WKO+ is far more powerful and sophisticated than their own performance management offerings, according to McGregor. "Because of this fact, and because you can create a basic Training Peaks account for free, we encourage every runner who uses a speed and distance device to also use Training Peaks WKO+, whether or not they use their device-specific performance management application as well," he adds.

In addition to specific device guidance, The Runner's Edge includes sample training plans and periodization guidelines--scalable to various fitness levels--for 5K, 10K, half-marathon, and marathon runners. A special chapter for triathletes explains how to integrate swim, bike, and run training within a unified performance management system.'