FIELD OF THE INVENTION- The present invention relates to an exercise apparatus, and more particularly to an interchangeable exercise apparatus that the user can easily change the exercise apparatus from dumbbell to barbell and vice versa. 
BACKGROUND OF THE INVENTION- Several appliances for home or indoor gymnastics have been developed. Among various exercising appliances, dumbbell is one of the most common and economic devices used in exercising the arms. Conventionally, a dumbbell has round weights joined by a short bar, by which it is lifted or swung about in the hand for muscular exercise. This structure of dumbbell has a fixed total weight once it is made. Therefore, different scale of dumbbell shall be used for different volume of training. Furthermore, when a dumbbell drops to the floor or ground, the floor of ground may be damaged by the round weights of the dumbbell easily. 
- In the field of weight lifting, similar to dumbbells, barbells comprise an elongated handle or bar that is loaded at either end with a plurality of weight plates. Assuming the weight plates are of the same weight relative to one another, the exercise weight provided by the dumbbell or barbell is adjusted by changing the number of weight plates installed on each end of the bar. The major difference between a dumbbell and barbell is the length of the bar that carries the weight plates. A dumbbell has a relatively short handle or bar that can be gripped by just one hand of the user. A barbell has a much longer bar that can be gripped by both hands of the user with the user's hands being spread apart along the length of the bar at approximately the width of the user's shoulders. 
- However, conventional dumbbells or barbells cannot be interchangeable, meaning easily transforming dumbbells into barbells and vice versa. Thus, if the user wishes to develop muscles in different portions of the body, he/she may have to separately purchase barbells and dumbbells, which may cause some inconvenience. Therefore, there remains a need for a new and improved exercise apparatus that can easily transform barbells into dumbbells and vice versa to overcome the problems stated above. 
SUMMARY OF THE INVENTION- It is an object of the present invention to provide a physical exercise equipment set to enable the user to easily transform one exercise apparatus to another. 
- It is another object of the present invention to provide an adjustable barbell and dumbbells so the user can add the weighted portions to the barbell and dumbbells according to the user's training plans and preferences. 
- In one aspect, a dumbbell may include a handle, a pair of weighted units located at two opposite ends of the handle, and a securing unit to secure each weighted unit in a predetermined position on the handle. In one embodiment, the two weighted portions can be identical and symmetrically disposed at the opposite ends of the handle. More specifically, the weighted portion has a through hole and the handle has an elongated threaded portion at two opposite ends, and the securing unit is configured to move along the threaded portion. The weighted portion is inserted into the handle from the threaded portion until one side of the weighted portion reaches a stopping edge on the handle, while the other side thereof is secured by the securing unit on the threaded portion. 
- Once the weighted portion is secured by the securing unit on each side of the handle, the user can hold the handle of the dumbbell to exercise on either one hand or two hands. It is noted that the weighted portion can be added on each side of the handle according to the user's training plans and preferences. 
- As discussed above, when the user purchases one type of exercise apparatus, such as dumbbells, it is difficult for the user to change the existing exercise apparatus to another type to exercise other portions of the body. Likewise, when the user purchases a traditional barbell, it is also difficult to alter it to a smaller exercise equipment such as dumbbells. 
- In another aspect, two dumbbells can turn into a barbell with a simple addition of an elongated connecting bar. More specifically, for each dumbbell, the user can first disengage the securing unit from one side of the threaded portion and the weighted portion can be taken out from the threaded portion of the handle. The connecting bar has two ends and each end has a threaded engaging hole to threadedly engage with the threaded portion of the dumbbell. 
- After removing one weighted unit from each of the dumbbells, the threaded portion can be inserted and threadedly engaged with the threaded engaging hole on each side of the connecting bar to form the barbell. In one embodiment, the weighted portion can be added to each side of the barbell according to the user's training plans and preferences. 
BRIEF DESCRIPTION OF THE DRAWINGS- FIG. 1 is a schematic view of an adjustable dumbbell in the present invention. 
- FIG. 2 illustrates a schematic view of a user exercising with adjustable dumbbells in the present invention. 
- FIG. 3 illustrates an exploded view of the adjustable dumbbell and a barbell in the present invention. 
- FIG. 4 is a schematic view of an adjustable barbell in the present invention. 
- FIG. 5 illustrates a schematic view of a user exercising with the adjustable barbell in the present invention. 
DETAILED DESCRIPTION OF THE INVENTION- The detailed description set forth below is intended as a description of the presently exemplary device provided in accordance with aspects of the present invention and is not intended to represent the only forms in which the present invention may be prepared or utilized. It is to be understood, rather, that the same or equivalent functions and components may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. 
- Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices and materials similar or equivalent to those described can be used in the practice or testing of the invention, the exemplary methods, devices and materials are now described. 
- All publications mentioned are incorporated by reference for the purpose of describing and disclosing, for example, the designs and methodologies that are described in the publications that might be used in connection with the presently described invention. The publications listed or discussed above, below and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. 
- As used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes reference to the plural unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the terms “comprise or comprising”, “include or including”, “have or having”, “contain or containing” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. As used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
- It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
- In one aspect, as shown inFIGS. 1 to 3, adumbbell100 may include ahandle110, a pair ofweighted units112 located at two opposite ends of thehandle110, and asecuring unit114 to secure eachweighted unit112 in a predetermined position on thehandle110. In one embodiment, the two weightedportions112 can be identical and symmetrically disposed at the opposite ends of thehandle110. More specifically, theweighted portion112 has a throughhole1121 and thehandle110 has an elongated threadedportion1101 at two opposite ends, and thesecuring unit114 is configured to move along the threadedportion1101. The weightedportion112 is inserted into thehandle110 from the threadedportion1121 until one side of the weightedportion112 reaches a stoppingedge1102 on thehandle110, while the other side thereof is secured by the securingunit114 on the threadedportion1101. 
- As shown inFIG. 2, once theweighted portion112 is secured by the securingunit114 on each side of thehandle110, the user can hold thehandle110 of thedumbbell100 to exercise on either one hand or two hands. It is noted that the weightedportion112 can be added on each side of thehandle110 according to the user's training plans and preferences. 
- As discussed above, when the user purchases one type of exercise apparatus, such as dumbbells, it is difficult for the user to change the existing exercise apparatus to another type to exercise other portions of the body. Likewise, when the user purchases a traditional barbell, it is also difficult to alter it to a smaller exercise equipment such as dumbbells. 
- In another aspect, as shown inFIG. 3, twodumbbells100 can turn into abarbell200 with a simple addition of an elongated connectingbar120. More specifically, for eachdumbbell100, the user can first disengage the securingunit114 from one side of the threadedportion1101 and the weightedportion112 can be taken out from the threadedportion1101 of thehandle110. The connectingbar120 has two ends and each end has a threadedengaging hole1201 to threadedly engage with the threadedportion1101 of thedumbbell100. 
- As shown inFIGS. 3 to 5, after removing oneweighted unit112 from each of thedumbbells100, the threadedportion1101 can be inserted and threadedly engaged with the threadedengaging hole1201 on each side of the connectingbar120 to form thebarbell200. In one embodiment, as shown inFIG. 4, theweighted portion112 can be added to each side of thebarbell200 according to the user's training plans and preferences. 
- Having described the invention by the description and illustrations above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Accordingly, the invention is not to be considered as limited by the foregoing description, but includes any equivalent.