diff --git a/src/garmin/ActivityId.scala b/src/garmin/ActivityId.scala
index 1ec74bf..855efe7 100644
--- a/src/garmin/ActivityId.scala
+++ b/src/garmin/ActivityId.scala
@@ -7,6 +7,7 @@ import scala.scalajs.js
 import org.scalajs.dom.HTMLElement
 
 import core.*
+import core.Gauge.{BeatPerMinute as bpm, StepPerMinute as spm}
 import core.service.Fetch
 
 opaque type ActivityId = String
@@ -14,30 +15,34 @@ opaque type ActivityId = String
 object ActivityId:
   def apply(s: String): ActivityId = s
 
-  given inject(using
+  given (using
+    Predicate[(bpm, spm, Intensity), js.Dynamic],
     Fetch[Get, js.Dynamic],
     Inject[History[js.Dynamic]]
   ): Inject[List[ActivityId]] with
     extension (ids: List[ActivityId])
       def inject(e: HTMLElement): Unit =
-        for case Some(h) :: t <- Future.sequence(ids.map(splits)) do (h -> t.map(_.toList).flatten).inject(e)
+        for case Some(h) :: t <- Future.sequence(ids.map(splits[(bpm, spm, Intensity)])) do
+          (h -> t.map(_.toList).flatten).inject(e)
 
-  private def splits(id: ActivityId)(using Fetch[Get, js.Dynamic]) =
+  private def splits[T](id: ActivityId)(using Fetch[Get, js.Dynamic], Predicate[T, js.Dynamic]) =
     inline def url      = s"https://connect.garmin.cn/activity-service/activity/$id/splits"
     inline def referrer = s"https://connect.garmin.cn/modern/activity/$id"
 
-    for d <- Get(url, referrer).request yield d.asInstanceOf[Splits].lapDTOs.toList.filter(_.isActive) match
+    for d <- Get(url, referrer).request
+    yield d.asInstanceOf[Splits].lapDTOs.toList.filter(Predicate[T, js.Dynamic]) match
       case h :: t => Some(h -> t)
       case _      => None
 
-  private trait Lap extends js.Object:
-    def intensityType: js.UndefOr[String]
-
-  extension (l: Lap)
-    private inline def isActive =
-      l.intensityType == "ACTIVE" || l.intensityType == "INTERVAL" || l.intensityType == js.undefined
-
   private trait Splits extends js.Object:
-    def lapDTOs: js.Array[Lap & js.Dynamic]
+    def lapDTOs: js.Array[js.Dynamic]
+
+  sealed trait Intensity
+  object Intensity:
+    private trait Lap extends js.Object:
+      def intensityType: js.UndefOr[String]
 
+    given Predicate[Intensity, js.Dynamic] = Predicate: a =>
+      val t = a.asInstanceOf[Lap].intensityType
+      t == "ACTIVE" || t == "INTERVAL" || t == js.undefined
 end ActivityId
diff --git a/src/garmin/Predicate.scala b/src/garmin/Predicate.scala
new file mode 100644
index 0000000..a5b7061
--- /dev/null
+++ b/src/garmin/Predicate.scala
@@ -0,0 +1,18 @@
+package garmin
+
+import core.Read
+
+opaque type Predicate[T, A] = A => Boolean
+object Predicate:
+  def apply[T, A](f: A => Boolean): Predicate[T, A]        = f
+  def apply[T, A](a: A)(using p: Predicate[T, A]): Boolean = p(a)
+
+  given [A]: Predicate[EmptyTuple, A]                                                          = _ => true
+  given [H, T <: Tuple, A](using h: Predicate[H, A], t: Predicate[T, A]): Predicate[H *: T, A] = a => h(a) && t(a)
+
+  given [T, A, B](using Read[T, A, B]): Predicate[T, A] = a =>
+    try
+      Read[T, A, B](a)
+      true
+    catch case _ => false
+end Predicate