## 1 Introduction  
Monitoring physical activity, e.g., training load and energy expenditure (EE), is important to optimize the training process in various sports [1, 2, 3]. Knowledge about EE allows for adaptations of training sessions and structures according to sport-specific demands in training and competition. To our best knowledge, EE is mainly used for monitoring cyclical movements (running, cycling, XC skiing) because these movements are easily imitable under laboratory conditions. For example, EE has been obtained via indirect calorimetry (EE\({}_{\text{Spiro}}\)), often considered as the gold standard for the calculation of EE, to compare the effects of different shoe materials during running [4]. EE\({}_{\text{Spiro}}\) analyses has also been applied in cycling to assess the metabolism on an energy and exergy basis [5]. In sports that are based on acyclic movements (e.g., team sports), the assessment of EE is controversially discussed, and spiroergometry is often unfeasible in competition and/or training [6]. Studies on EE in team sports collected respiratory data based on movements that may be common in general but not appropriately reflect the sport-specific demands [7, 8]. Due to this deficit, the metabolic power model of EE determined by local position measuring (LPM) data was developed [9]. The strength of this method is its applicability in competition because EE (EE\({}_{\text{LPM}}\)) can be determined via an LPM system, and no spiroergometry system is necessary to estimate EE. The calculation of EE\({}_{\text{LPM}}\) is based on the translation of tilt angles between the ground and the center of mass during accelerated flat running to incline angles during constant uphill running, for which EE is known [10]. Spiroergometry and LPM data were collected simultaneously in soccer [11; 12] and rugby [13] to compare the two methods of EE determination in team sports. An underestimation of \(\text{EE}_{\text{LPM}}\) compared to \(\text{EE}_{\text{Spiro}}\) was found when performing sport-specific movements [11; 12; 13]. One explanation is that LPM usually measures only horizontal position data, which do not reflect EE for specific movements like collisions, jumps, passes, and shots; thus, the demand for such actions is not considered properly in LPM data [12; 13]. Team sports like team handball are very complex and characterized by multiple sport-specific movements like accelerations, decelerations, change of directions, jumps, passes, throws, and tackles in offense and defense [14; 15; 16; 17]. A systematic comparison of \(\text{EE}_{\text{LPM}}\) and \(\text{EE}_{\text{Spiro}}\) determination in team handball should therefore include these specific movements in the test protocol [18]. We expected a systematic underestimation of \(\text{EE}_{\text{LPM}}\) also in team handball, as shown previously [11; 12; 13]. However, this supposed underestimation of \(\text{EE}_{\text{LPM}}\) does not exclude a possible significant correlation between both methods in EE if the difference is systematic. It represents a remarkable chance to advance the application of EE in team sports and was never investigated in previous studies. A systematic correlation between \(\text{EE}_{\text{LPM}}\) and \(\text{EE}_{\text{Spiro}}\) would enable the development of a regression model to predict valid \(\text{EE}_{\text{Spiro}}\) (the gold standard method) based on LPM data. Consequently, EE could be determined accurately without limitation in training and competition. The game-based performance test (GBPT), was specifically developed and validated for team handball, including the team handball specific movements, durations, and intensities, as well as physiological and perceptional effects measured during competition [19]. Therefore, the GBPT reflects the EE demands in team handball and, in contrast to team handball training or competition, allows for spiroergometry measurement. Consequently, the GBPT is suitable to determine valid EE in team handball and to compare \(\text{EE}_{\text{LPM}}\) and \(\text{EE}_{\text{Spiro}}\).